Part 1: The Tanker Crisis in the Gulf

Tensions between Iran and the outside world have escalated since an attack on four tankers on May 12 near the Strait of Hormuz, which was followed by an attack on two more tankers on June 13. Both attacks occurred in the Gulf of Oman. The Persian Gulf flows through the Strait of Hormuz into the Gulf of Oman. On July 4, the British Royal Navy seized an Iranian tanker carrying oil to Syria. In what seemed like a response, Iranian vessels harassed a British tanker while entering the Strait of Hormuz on July 11. Then on July 19, the IRGC seized a British oil tanker for "violating international maritime rules" while passing through the Strait of Hormuz. Tehran had threatened to retaliate against British "piracy" after Britain refused to release the Iranian vessel seized off the coast of Gibraltar.

After the second attack, the tanker association INTERTANKO warned about dangers to global energy trade. “Following two attacks on Member vessels this morning, I am extremely worried about the safety of our crews going through the Strait of Hormuz,” said INTERTANKO chairman Paolo d’Amico. “We need to remember that some 30 percent of the world’s (seaborne) crude oil passes through the Straits. If the waters are becoming unsafe, the supply to the entire Western world could be at risk,” he added. Jakob P. Larsen, chief of maritime security for BIMCO, the world’s largest international shipping association, said his industry “views this as an escalation of the situation, and we are just about as close to a conflict without there being an actual armed conflict, so the tensions are very high.”Within hours, the latest attacks pushed oil prices up by as much as four percent.

Tanker Crisis Map


Countries Contributing to Maritime Security in the Persian Gulf

In various forms, the following countries have committed to work alongside or collaborate with the U.S.-led maritime security mission, Operation Sentinel. Their official announcements are listed by the following dates in the chronology:

  • United States (July 29)
  • Great Britain (August 5)
  • Israel (August 6)
  • Bahrain (August 19)
  • Australia (August 21)


The two tankers – one owned by Japan and one owned by Norway – were attacked near the Strait of Hormuz in the Gulf of Oman. The second ship, the Front Altair, may have been targeted by a torpedo, according to CPC Corp, which chartered the ship. The Front Altair’s crew of 23 were reportedly rescued by the Hyundai Dubai vessel and were transferred to an Iranian navy vessel bound for the Iranian port of Bandar Abbas. Iranian state media claimed that all 44 crew members from both ships were rescued by Iranian teams.

The U.S. Navy deployed in the region offered aid in dealing with the two damaged tankers. “U.S. Naval Forces in the region received two separate distress calls at 6:12 a.m. local (Bahrain) time and a second one at 7:00 a.m. U.S. Navy ships are in the area and are rendering assistance," a U.S. Navy spokesman said.

Secretary of State Mike Pompeo blamed the attacks – and other incidents in Iraq and Afghanistan – on Iran. He said the U.S. judgement was based on intelligence, “weapons used, the level of expertise needed to execute the operation, recent similar Iranian attacks on shipping, and the fact that no proxy group operating in the area has the resources and proficiency to act with such a high degree of sophistication.” Senior U.S. officials said an unexploded mine was sighted on the side of one of the tankers, according to The Associated Press. They said Washington was considering a plan to provide military escorts for merchant ships. 


France condemned the attack. “We have learned that a disturbing incident involving two tankers in the Arabian Sea has occurred today, in the broader context of rising tensions in the region, as evidenced also by the attack on the [Abha airport] in Saudi Arabia yesterday, which we firmly condemned,” a Ministry of Foreign Affairs spokesperson told CNN. On June 12, a missile fired by an Iranian-backed militia in Yemen hit the arrivals hall of Abha airport in southwest Saudi Arabia. The kingdom reported 26 people were injured. “We call all the actors concerned, with whom we are in constant contact, to show restraint and de-escalation,” the French statement added. “We also would like to underscore our attachment to the freedom of navigation, which must absolutely be preserved.” German expressed concern too. “An escalation of the situation is dangerous, these are events that could lead to escalation. We need de-escalation and all sides must contribute to that,” Foreign Minister Heiko Maas said at a news conference. He had returned from a trip to Iran to discuss the growing tensions with Iran. The British government expressed deep concern and said it was in contact with “local authorities and partners in the region.”

Russia warned against hasty judgments about who might be responsible for the attacks. “Lately we have been seeing a strengthening campaign of political, psychological and military pressure on Iran. We wouldn’t want the events that have just happened, which are tragic and shook the world oil market, to be used speculatively to further aggravate the situation in an anti-Iranian sense,” Deputy Foreign Minister Sergei Ryabkov said according to RIA. Germany, which is one of six nations that negotiated a nuclear deal with Iran in 2015, called the “extremely worrying.”

Reports of the attack coincided with Japanese Prime Minister Shinzo Abe’s meeting with Iranian Supreme Leader Ayatollah Ali Khamenei on June 13. Iranian Foreign Minister Mohammad Javad Zarif said the timing was beyond “suspicious.” Abe was on a mission to deescalate tensions between Iran and the United States. But Khamenei told Abe that there was no point in responding to a message conveyed by Abe from President Donald Trump, who visited Japan on May 27. “I do not see Trump as worthy of any message exchange, and I do not have any reply for him, now or in future,” Khamenei told Abe, according to Iranian state media.


The four ships hit on May 12 – two Saudi-flagged, an Emirati-flagged and an Norwegian-flagged – were positioned off the coast of the United Arab Emirates (UAE). No injuries were reported. U.S. officials alleged that limpet mines were used and that Iran was the most likely culprit, but they did not publicize definitive evidence. Iran denied any involvement. The UAE, Saudi Arabia and Norway presented preliminary findings of their inquiry to the U.N. Security Council on June 7. They blamed an unidentified state actor “with significant operational capacity” for the attacks. “We believe the responsibility for this attack lies on the shoulders of Iran,” Saudi Arabia’s U.N. ambassador, Abdallah al Mouallimi, told reporters after the briefing. 

Saudi Arabia also blamed Iran for the airport attack. "The Iranian regime is the only party in the region that has been pursuing reckless escalation, through the use of ballistic missiles and UAVs to directly target civilian installations and innocent civilians,” Deputy Defense Minister Prince Khalid bin Salman said. “The continuation of the Iranian regime’s aggression and reckless escalation, whether directly or through its militias, will result in grave consequences."

The following is a chronology of the tanker attacks and subsequent fallout. 


May 12 - Four ships off the coast of the United Arab Emirates (UAE) were reportedly sabotaged, including two Saudi Arabian oil tankers. One was due to take a delivery of Saudi oil to the United States. “Fortunately, the attack didn't lead to any casualties or oil spill; however, it caused significant damage to the structures of the two vessels,” said Khalid al-Falih, the kingdom’s energy minister.

The UAE did not speculate on who might have been responsible, but the alleged attack came as the United States warned that “Iran or its proxies” could target maritime traffic in and around the Persian Gulf. Iran was the most likely culprit, according to a U.S. official who spoke with Reuters on condition of anonymity, but the United States did not offer conclusive proof. On May 13, Trump warned that Iran “will suffer greatly” if it attacks U.S. interests in the Gulf. “We will see what happens with Iran. If they do anything, it’ll be a big mistake,” he told the press. But Iran denied any involvement and accused the Trump administration officials of trying to frame it.


May 15 – The New York Times reported that photographs of missiles on small boats in the Persian Gulf were the cause of the White House’s increased warnings about the threat from Iran. The concern was that the IRGC would fire them at U.S. naval vessels or disrupt commercial shipping. Intelligence also suggested American troops in Iraq could be targeted by militias with ties to Tehran.

Secretary Pompeo spoke with Omani Sultan Qaboos bin Sa'id Al Sa'id about “Iranian threats to the Gulf region” in a telephone call. Oman, located next to the Strait of Hormuz, has historically been an interlocutor between Iran and the United States.

May 17 – U.S. officials told NBC News that an intelligence assessment, including photographs and forensics, found it was “highly likely” that Iran or one of its proxies were responsible for the tanker attack.

A Defense Department official and a congressional official told The New York Times that Iran unloaded missiles from at least two small boats in its territorial waters. The move was seen as a de-escalation in tensions.

May 29 – National Security Advisor Bolton told reporters that it was “clear that Iran is behind” the attack on tankers. “There's no doubt in anybody's mind in Washington who's responsible for this,” he added. “Who else would you think is doing it? Someone from Nepal?” Bolton did not provide evidence. Iran’s foreign ministry spokesman, Abbas Mousavi, called the charge “ludicrous.”

May 24 – Acting Secretary of Defense Shanahan confirmed that 1,500 additional troops will be deployed to the region.

At a press briefing, the Pentagon clarified that 900 additional troops will be sent to the region and 600 personnel manning Patriot missile batteries would have their deployment extended. Acting Assistant Secretary of Defense Katie Wheelbarger emphasized that U.S. policy with respect to Iran had not changed. “As the president and the secretary have been clear, we do not seek conflict with Iran. We do not see these additional capabilities as urging hostilities. We see them as defensive in nature,” she said. Rear Admiral Michael Gilday, the director of the Joint Staff, said the IRGC was responsible for the attack on tankers earlier in May. He said limpet mines were used but did not specify how they were delivered.

June 13 – The hull of the Panama-flagged tanker Kokua Courageous was damaged above the water line, Bernhard Schulte Ship management reported. It was attacked twice in three hours before all crew members were evacuated. The ship was owned by the Japanese company Kokyua Sangyo.

A second ship, the Marshall Islands-flagged Front Altair was “suspected of being hit by a torpedo,” according to Taiwanese refiner CPC Corp. Some 75,000 tons of naptha were set ablaze, but the vessel was still afloat, according to Norwegian owner Frontline. Iranian state media had reported that it had sunk. The crew of 23 were rescued by the Hyundai Dubai vessel and were transferred to an Iranian navy vessel bound for the Iranian port of Bandar Abbas. Iranian state media claimed that all 44 members of the ships’ crews were rescued by Iranian teams, citing an unnamed source.

The Bahrain-based U.S. Navy Fifth Fleet also said it was responding to distress calls. White House Press Secretary Sarah Sanders said President Trump was briefed on the attacks. “The U.S. Government is providing assistance and will continue to assess the situation,” she added.

Russia warned against rushing to blame the attack on a country or group. “I would take the opportunity to warn against hasty conclusions, against attempts to lay the blame at the door of those we don’t like,” Deputy Foreign Minister Sergei Ryabkov said according to RIA. “Lately we have been seeing a strengthening campaign of political, psychological and military pressure on Iran. We wouldn’t want the events that have just happened, which are tragic and shook the world oil market, to be used speculatively to further aggravate the situation in an anti-Iranian sense.”

Reports of the attack coincided with Japanese Prime Minister Shinzo Abe’s meeting with Iranian Supreme Leader Ayatollah Ali Khamenei. Iranian Foreign Minister Mohammad Javad Zarif said the timing was beyond “suspicious.” 


Abe was on a mission to deescalate tensions between Iran and the United States. But Khamenei told Abe that there was no point in responding to a message conveyed by Abe from President Donald Trump, who visited Japan on May 27 . “I do not see Trump as worthy of any message exchange, and I do not have any reply for him, now or in future,” Khamenei told Abe, according to Iranian state media.

President Trump responded with a tweet:


In the afternoon, Secretary of State Mike Pompeo blamed the attacks – and other incidents in Iraq and Afghanistan – on Iran. He said the U.S. judgement was based on intelligence, “weapons used, the level of expertise needed to execute the operation, recent similar Iranian attacks on shipping, and the fact that no proxy group operating in the area has the resources and proficiency to act with such a high degree of sophistication.” 

In the evening, U.S. Central Command (CENTCOM) released a video allegedly showing Iranian sailors removing a mine from the Kokura Courageous’ hull. 


Iranian Foreign Ministry Spokesman Abbas Mousavi called U.S. accusations against Tehran “alarming.” “We are responsible for ensuring the security of the Strait and we have rescued the crew of those attacked tankers in the shortest possible time,” he said in an interview with Iranian state radio.


June 14 – President Trump, in an interview on “Fox & Friends,” accused Iran of perpetrating the attacks. “Iran did do it,” he said. “They didn’t want the evidence left behind. They don’t know that we have things that we can detect in the dark that work very well. We have that. It was them that did it,” he added, referring the CENTCOM video. 


June 17 – U.S. Central Command (CENTCOM) released high-resolution photos allegedly showing an IRGC boat removing an unexploded mine from the Kokuka Courageous. Additional photos showed a magnetic device that the mine was attached to and damage to the tanker’s hull. 


Acting Defense Secretary Shanahan authorized the deployment of 1,000 additional troops to the Middle East. “The recent Iranian attacks validate the reliable, credible intelligence we have received on hostile behavior by Iranian forces and their proxy groups that threaten United States personnel and interests across the region,” he said. Shanahan reiterated that the United States was not seeking a conflict with Iran and that the action was solely “defensive.”

President Donald Trump referred to recent Iranian attacks as “very minor” in an interview with Time. “If you look at the rhetoric now compared to the days when they were signing that agreement [the 2015 nuclear deal], where it was always ‘death to America, death to America, we will destroy America, we will kill America,’ I’m not hearing that too much anymore, and I don’t expect to,” he added.

June 18 – President Hassan Rouhani declared that Iran “will not wage war on any nation,” after the United States announced the deployment of 1,000 additional troops to the region.  “Despite all of the Americans’ efforts in the region and their desire to cut off our ties with all of the world and their desire to keep Iran secluded, they have been unsuccessful,” he said in a speech on state television.

IRGC Commander Hossein Salami claimed that Iranian missiles are capable of hitting “carriers in the sea” and “difficult to intercept.” He added that improved Iranian missile technology has altered the balance of power in the region.

July 4- British marines seized an Iranian-owned and Panamanian-flagged oil tanker off the coast of Gibraltar for transporting oil to Syria in violation of E.U. sanctions. The seizure was conducted at the request of the United States, according to the Spanish government. “We welcome international partners’ resolve in upholding and enforcing these sanctions,” said a State Department spokesman. 


Tehran condemned the act as an illegal seizure and said the vessel was not heading to Syria. “These days we witnessed a threatening act from the government of England in the Strait of Gibraltar against a tanker from the Islamic Republic of Iran. This is an incorrect and wrong action, an action similar to maritime robbery... certainly these kind of robberies will not be tolerated,” said Iranian Defense Minister Amir Hatami. 

July 10  President Hassan Rouhani warned that Britain would face “consequences” for the seizure of an Iranian oil tanker on July 4. “You (Britain) are the initiator of insecurity and you will realize the consequences later,” he said on state television.  

July 11 – Three IRGC vessels attempted to block a British tanker from passing through the Strait of Hormuz according to the British government. The Iranian boats reportedly withdrew after verbal warnings from a Royal Navy warship that was escorting the tanker. “We are concerned by this action and continue to urge the Iranian authorities to de-escalate the situation in the region,” the British government said 

Iran denied any attempt to harass the British tanker. Foreign Minister Mohammad Javad Zarif called the British allegations “worthless.” “Apparently the British tanker has passed. What they have said themselves and the claims that have been made are for creating tension and these claims have no value,” he said. 

The United Nations called for freedom of movement for maritime traffic in the Gulf following the incident. U.N. Secretary-General Antonio Guterres urged all parties to conduct “maximum restraint” in the Gulf and warned that a new confrontation “would be a catastrophe.” 

July 12 – Iranian Foreign Ministry spokesman Abbas Mousavi urged the British government to release the Iranian tanker seized on July 4. “The claims are without legal basis and we advise [Britain] not to start a dangerous and unclear game under the influence of the Americans,” Mousavi warned.  

July 13 – Iranian Foreign Minister Mohammad Javad Zarif told his British counterpart Jeremy Hunt that Iran would continue to export oil under any circumstances. Hunt reassured Zarif that Britain respected Iran’s right to export oil as long as the destination was not Syria. Hunt added that Britain would release the Iranian tanker if it received assurances that it would not continue to Syria.  


July 15 – An oil tanker disappeared in the Persian Gulf while traveling in Iranian waters. The Panamanian-flagged vessel switched off its transponder off the coast of Iran’s Qeshm Island in the Strait of Hormuz. Tracking data from the tanker revealed that it was heading towards Fujairah before suddenly turning toward Iranian waters. “Could it have broken down or been towed for assistance? That’s a possibility. But the longer there is a period of no contact, it’s going to be a concern,” said a U.S. Defense official.  

Iranian Supreme Leader Ayatollah Ali Khamenei vowed to respond to British “piracy” of an Iranian oil vessel on July 4.  “Evil Britain commits piracy and steals our ship ... and gives it a legal appearance. Iran and those who believe in our system will not leave such evil deeds unanswered,” Khamenei warned.   

July 17 – Iran claimed that it towed an oil tanker from the Strait of Hormuz back to Iranian waters for repairs after receiving a distress call. “A foreign oil tanker encountered a problem in the Persian Gulf due to technical failure, and Iranian forces, in accordance with international regulations, rushed to help it after receiving a distress call,” Foreign Ministry spokesman Abbas Mousavi said. Emirati and U.S. officials, however, said the tanker never sent a distress signal.   

The tanker had not been claimed by a specific country despite initial reports linking it to a company in the UAE. U.S. officials were still unsure whether the tanker was seized by Iran or towed back due to mechanical issues. 

July 18 – The IRGC announced that it had seized a foreign tanker smuggling oil on July 14. “The vessel that Iran towed to its waters after receiving a distress call, was later seized with the order from the court as we found out that it was smuggling fuel,” the Revolutionary Guard said on state television. The statement added that 12 foreign crew members were detained and 1 million liters (264,000 gallons) of fuel were confiscated. The identity and origin of the ship remained unknown.  

Iranian state news agency Press TV released a video showing IRGC fast boats seizing “The Riah,”a Panamanian-flagged ship that was reported missing in the Strait of Hormuz on July 15.  

July 19  The IRGC seized two foreign oil tankers in the Strait of Hormuz. The British-flagged Stena Impero was heading towards Saudi Arabia when it abruptly veered toward the Iranian island of Qeshm, where the IRGC has a large naval base. The ship’s owner, Stena Bulk, said that it was unable to contact the vessel or its 23-man crew as it deviated toward Iran. The company said the tanker “was approached by unidentified small crafts and a helicopter during transit in the Strait of Hormuz while the vessel was in international waters.” On July 20, Fars news agency, linked to the IRGC, released a video that showed masked guards rappelling onto the Stena Impero from a helicopter. The ship was taken to Bandar Abbas, a port on Iran's southern coast, according to Iranian news outlets. The crew was instructed to remain on the vessel while Iranian officials carried out an investigation. 

The IRGC confirmed it had intercepted the Stena Impero for violating international maritime regulations. "UK tanker ship, Stena Impero, has been detained by the vessels unit of the IRGC Navy's First Naval Zone at the request of the Ports and Maritime Organization's office of Hormuzgan province for disregarding international maritime rules and regulations as it was passing through the Strait of Hormuz this afternoon," the IRGC said in a statement.  

U.S. officials reported that a second tanker, the Liberian-flagged and British-operated Mesdar, was seized by the IRGC half an hour after the first tanker. The Mesdar made a similar northern course change toward Iran. The Mesdar's managing company, Norbulk Shipping, later announced that the vessel had been boarded by armed guards but allowed to continue on its route after passing an inspection. “Communication has been re-established with the vessel and Master confirmed that the armed guards have left and the vessel is free to continue the voyage. All crew are safe and well," the company said.    

President Trump condemned Iran’s seizure of the vessels and said he would discuss the matter with the United Kingdom. "This only goes to show what I'm saying about Iran. Trouble. Nothing but trouble," Trump said. "It goes to show you I was right about Iran." 


Earlier in the day, a court in Gibraltar granted the government authority to detain Iran’s Grace 1 tanker for an additional month. “At a private meeting of the Supreme Court on an application by the Attorney General, the Court has extended the period of detention of the vessel, Grace 1, for a further 30 days and has set a new hearing for 15 August 2019,” the Gibraltar government said.  

The Pentagon announced a “multinational maritime effort” called Operation Sentinel “to increase surveillance of and security in key waterways in the Middle East to ensure freedom of navigation in light of recent events in the Arabian Gulf region.” The campaign would provide coordinated escorts for the flagged vessels of participating nations. U.S. Central Command also approved the deployment of 500 troops to Saudi Arabia as “an additional deterrent” to Iran. Riyadh accepted the basing agreement that placed U.S. combat troops in Saudi Arabia for the first time in over a decade. 

July 22 – Britain announced a European-led “maritime protection mission” to safeguard international shipping lanes. “It is with a heavy heart that we are announcing this increased international presence in the Gulf, because the focus of our diplomacy has been on de-escalating tensions in the hope that such changes would not be necessary,” said Foreign Secretary Jeremey Hunt. London claimed it would coordinate with the United States’ Operation Sentinel campaign but launched its own initiative to include European countries that would not contribute to a U.S.-led force.  

Prime Minister Theresa May called Iran's seizure of the British tanker illegal and demanded the release of the vessel and its crew. "We do not seek confrontation with Iran but it is unacceptable and highly escalatory to seize a ship going about legitimate business through internationally recognized shipping lanes," May said.

July 23 – Iranian Foreign Minister Mohammad Javad Zarif congratulated Boris Johnson on becoming Britain’s new prime minister. He added that Iran did not want a conflict with Britain but vowed Tehran would protect itself in the Persian Gulf.  


France, Italy, and Denmark supported Britain’s maritime security initiative at an E.U. meeting in Brussels. “Britain’s request, rather than Washington’s, makes it easier for Europeans to rally round this,” said a senior E.U. diplomat. “Freedom of navigation is essential, this is separate from the U.S. campaign of maximum pressure on Iran.” British foreign minister Jeremy Hunt made it clear that the campaign would not directly involve the European Union, NATO, or the United States.  

Iran rejected Britain’s maritime proposal, claiming it would create more instability in the region. “There is no need to form a coalition because these kinds of coalitions and the presence of foreigners in the region by itself creates insecurity, and other than increasing insecurity it will not achieve anything else,” said Iranian Vice President Eshaq Jahangiri. 

July 24 – President Hassan Rouhani said Iran would consider releasing a British tanker seized on July 19 if Britain agreed to release the Iranian vessel it seized off Gibraltar on July 4. “We do not seek the continuation of tension with some European countries,” Rouhani said. “Should they be committed to international frameworks and give up their wrong actions, including what they did in Gibraltar, they will receive a proportional response from Iran.” 

Sweden led negotiations between Iran, Britain, and other countries regarding a British tanker seized by Tehran on July 19. “Sweden is concerned by developments in the Strait of Hormuz. For Sweden and the EU it is vital that freedom of navigation is protected. Given the very serious situation in the region, it is also important that the measures taken help to ease tensions,” said the  foreign ministry. 

July 28 – Omani and Iranian officials met in Tehran to discuss navigation through the Strait of Hormuz. Iranian President Hassan Rouhani emphasized the need for greater coordination between the two countries. “The presence of foreign forces will not only not help the security of the region, but will be the main factor for tension,” he said. 

July 29 – The British Foreign Office announced the arrival of a second Royal Navy warship, the HMS Duncan, in the Persian Gulf. HMS Duncan joined the HMS Montrose that had already escorted 35 British vessels through the Strait of Hormuz. “Freedom of Navigation in the Strait of Hormuz is vital not just to the UK, but also our international partners and allies. Merchant ships must be free to travel lawfully and trade safely, anywhere in the world," said Defense Secretary Ben Wallace.

Iran released an audio exchange between the IRGC and a British warship before the seizure of a British tanker on July 19. The Iranian officer warned the Royal Navy not to interfere with the operation. 


July 30 – Iranian and UAE officials met in Tehran to discuss maritime security for the first time in six years. The meeting signaled a de-escalation in Gulf tensions that ignited when four oil tankers were sabotaged off the coast of the UAE on May 12.

July 31  Foreign Minister Heiko Maas announced that Germany would not join Operation Sentinel, the U.S. maritime security mission announced on July 22. “We consider the ‘maximum pressure’ strategy to be wrong. We do not want a further military escalation, we will continue to focus on diplomacy,” said Maas. On August 1, Japan also said it would not send warships to support the U.S. force, fearing a conflict with Iran.  

Aug. 1 – Britain announced that it would not exchange tankers with Iran. “We are not going to barter a ship that was detained legally with a ship that was detained illegally: that’s not the way that Iran will come in from the cold,” said British Foreign Secretary Dominic Raab. 

Aug. 4 – The IRGC said it seized an Iraqi tanker on July 31 in the Persian Gulf that was suspected of smuggling Iranian fuel. Seven crew members were detained and 185,000 gallons of oil were confiscated according to state media reports. The ship was towed back to Bushehr port and handed over to Iranian authorities. 

Secretary of State Mike Pompeo said the United States was “very confident” it could organize a maritime security coalition. “We got various degrees of response.  I think there’ll be some announcements coming out in the coming days, but needless to say, I think the purpose remains the same whether it’s an operation conducted under United States command and control or conducted by somebody else – a European partnership,” said Defense Secretary Mike Esper.  

Aug. 5 – Iranian Foreign Minister Mohammad Javad Zarif said Tehran would no longer tolerate maritime offenses in the Persian Gulf. “Iran used to forgo some maritime offences in ... (the) Gulf but will never close (its) eyes anymore,” said Zarif. “Iran is responsible for the security and safety of the Strait of Hormuz and the region.” 

Britain announced it would work with the United States in a “new international maritime security mission” to protect shipping in the Persian Gulf. “The deployment of Royal Navy assets is a sign of our commitment to our UK flagged vessels and we look forward to working alongside the US and others to find an international solution to the problems in the Strait of Hormuz,” said British Defence Secretary Ben Wallace. 

Aug. 6 – U.S. Defense Secretary Mark Esper welcomed Britain’s contribution to international maritime security in the Persian Gulf. “They're a very capable ally and partner, and we've always enjoyed that special relationship with them. So we look forward to getting into the details of how we will operate together in the straits,” said Esper. He added that other countries could announce their participation “in the coming days.” 

Aug. 9 – Iranian Foreign Minister Mohammad Javad Zarif said that any foreign military presence in the Persian Gulf would be a “source of insecurity” for Tehran. He specifically warned against Israel’s participation in a maritime security coalition.


Aug. 13 – Tehran said the Grace 1, an Iranian tanker seized by Britain off Gibraltar on July 4, would be released soon. “We believe that Grace 1 oil tanker will resume operation under Iranian flag in international waters in the very near future,” said Jalil Eslamithe deputy head of the Ports and Maritime Organization of Iran “Certain documents have been exchanged, which would help settle the issue.” 

Iran promised to reflag the vessel and set a new destination, according to the Wall Street Journal. A senior Gibraltar official, however, denied the reports.

Aug. 15 – Gibraltar released the Grace 1, an Iranian oil tanker impounded by Britain since July 4, despite a U.S. bid to prolong the detention. The United States applied to seize the Iranian tanker, but a Gibraltar court denied the request. Gibraltar Chief Minister Fabian Picardo said the United States could file a new appeal, but ordered the tanker’s immediate release after the Iranian government provided documentation that the ship would not deliver oil to Syria.  

The U.S. State Department accused the crew of the Grace 1 of providing material support to the IRGC. “The United States assesses that the M/T Grace I was assisting the Islamic Revolutionary Guard Corps (IRGC) by transporting oil from Iran to Syria. This could result in serious consequences for any individuals associated with the Grace I,” Spokesman Morgan Ortagus said.

Aug. 18 – The Adrian Darya 1, formerly named the Grace 1 and re-flagged from Panama to Iran, left Gibraltar for Kalamata, Greece after being detained by Britain for over a month. On August 16, the United States issued a warrant to seize the tanker and its 2.1 million barrels of crude oil. But the Gibraltar government said it could not comply with the request because U.S. sanctions against Iran did not apply in the European Union.  

Aug. 19 – Bahrain announced that it would join the U.S-led maritime coalition in the Persian Gulf. The announcement coincided with a meeting between Gen. Frank McKenzie, commander of the U.S. Central Command, and Bahraini King Hamad bin Isa Al-Khalifa. “The free flow of commerce throughout international waterways is a linchpin of the global economy, and we appreciate the Kingdom of Bahrain's leadership and support in preventing aggression from curtailing that freedom,” said McKenzie.  

Aug. 20 – The United States warned Greece not to assist an Iranian tanker released by Britain on August 18. “We have conveyed our strong position to the Greek government on the matter, as well as all ports in the Mediterranean that should be forewarned about facilitating this vessel,” the State Department said. Greek officials said the country had not received a request for the vessel to dock at its ports.

Greece said it would not aid the Iranian tanker. “We are sending a message that we are not prepared to facilitate the course of this ship to Syria, and this is a message that we have made very clear,” said Deputy Foreign Minister Miltiadis Varvitsiotis. He added that the tanker was too big to enter any Greek port anyway.  

Aug. 21 – Australia announced it would join the international coalition in the Persian Gulf to assure the security of merchant vessels through the Strait of Hormuz. Prime Minister Scott Morrison said Australia would provide a “modest, meaningful and time-limited" contribution including troops, a surveillance plane and a Navy frigate.

Aug. 26 – Tehran announced that it had sold the oil from the Adrian Darya 1 to an unnamed buyer. The Iranian tanker, formerly known as the Grace 1, was detained by Britain on July 4 for attempting to sell oil to Syria. “The Islamic Republic of Iran has sold the oil of this ship and now the owner and purchaser of this oil will decide the destination of the cargo,” said government spokesman Ali Rabiei 

Iran dispatched its most advanced destroyerSahandand a helicopter-carrying support ship to the Sea of Oman and the Gulf of Aden. Admiral Habibollah Sayyari, the chief of staff of Iran’s army, said the warships would “provide security for Islamic Republic vessels in international waters.”  

Britain also announced the deployment of an additional warship to the Persian Gulf. The Type 45 destroyer HMS Defender was redirected from its mission in the Pacific to assist two British warships already stationed in the Gulf.

Aug. 30 – The Adrian Darya 1, an Iranian tanker temporarily detained by Britain for attempting to sell oil to Syria, listed its destination as Iskenderun, Turkey. The Turkish port is only 125 miles away from its original destination of Baniyas, Syria. But Turkey’s Foreign Minister Mevlut Cavusoglu said the tanker was going to Lebanon and not Turkey. Lebanese officials, however, denied the reports and claimed they had not been in contact with the vessel.  

The tanker first listed its destination as Kalamata, Greece after it was released from detention in Gibraltar on August 18. It changed its destination to Mersin, Turkey on August 24 before removing a destination entirely.   

The United States sanctioned the Adrian Darya-1, which it accused of transporting 2.1 million barrels of Iranian crude oil on behalf of the IRGC. The U.S. Treasury also designated the ship’s captain, Akhilesh Kumar, for providing support to a terrorist organization.  

Sept. 3 – The Adrian Darya-1, an Iranian tanker designated by the United States for transporting oil on behalf of the IRGC, turned its tracker off near the coast of Syria. The ship sent its last signal between Cyprus and Syria while sailing north.  

Sept. 4 – Iran released seven crew members out of 23 from the British-flagged tanker, Stena Impero. Tehran seized the ship in the Strait of Hormuz on July 18 for allegedly “disregarding international maritime rules and regulations.” Iranian state television reported that the crew members were released on humanitarian grounds.  

Sept. 7 – The Adrian Darya-1, an Iranian tanker designated by the United States for transporting oil on behalf of the IRGC, was photographed by satellite off the coast of Tartus, Syria. The ship’s transponder remained off. Maritime experts believed the tanker was likely to conduct a ship-to-ship transfer to unload its crude cargo.  

Sept. 10 – Britain accused Iran of selling the Adrian Darya’s oil to the Assad regime in Syria. “Iran has shown complete disregard for its own assurances over Adrian Darya 1,” said British Foreign Minister Dominic Raab 

Sept. 11 - Iran confirmed the tanker had found a buyer but stopped short of saying it was sold to Assad. “EU sanctions cannot be extended to third countries. Despite numerous threats by America, the tanker sold its oil at sea to a private company and has not violated any obligation,” said Iran’s ambassador to Britain Hamid Baeidinejad 

Sept. 12 – Washington claimed it had evidence that Iran sold the Adrian Darya’s oil to the Assad regime. “The Iranian regime delivered oil to Syria, and that fuel goes straight into the tanks of troops that are slaughtering innocent Syrians,” said State Department spokeswoman Morgan Ortagus

Sept. 18 – Saudi Arabia announced that it would join the U.S.-led maritime security coalition, Operation Sentinel, in the Persian Gulf. “The kingdom’s accession to this international alliance comes in support of regional and international efforts to deter and counter threats to maritime navigation and global trade,” said state-run Saudi Press Agency. The announcement came as U.S. Secretary of State Mike Pompeo visited the region to build a coalition for “peaceful resolution.” 

Sept. 19 – The United Arab Emirates announced it would follow Saudi Arabia and join the international maritime mission to protect commercial shipping in the Persian Gulf.

Sept. 23 – Tehran said it would soon release the Stena Impero, a British tanker seized by Iran in the Strait of Hormuz on July 19. Ali Rabiei, Iran's government spokesperson, said the legal process had concluded, and the ship was “free to leave.” But the tanker remained in port at Bandar Abbas the following day without a timeline of its departure, according to Stena Bulk CEO Erik Hanell.

Sept. 27  Iran released the British-flagged Stena Impero tanker after a 10-week detention. The vessel was seized by the IRGC in the Strait of Hormuz on July 19 for “violating international maritime regulations.” Stena Bulk CEO Erik Hanell said the ship was headed to Dubai where the crew would disembark.

Oct. 3 – Satellite images showed the Adrian Darya tethered to a smaller Iranian-flagged tanker, Jasmine, off the coast of Syria. Maritime experts speculated that the Adrian Darya may have conducted a ship-to-ship transfer of its crude oil cargo. Iranian ships used offshore transfers to covertly deliver its oil to ships owned by countries including China and Syria.   


Oct. 11 – Iranian state media reported that the Sabiti, a tanker owned by the National Iranian Tanker Company (NITC), was struck by missiles in the Red Sea. Saheb Sadeghi, the NITC head of public relations, said the missiles were “possibly” fired from Saudi territory. But the National Iranian Oil Company later dismissed that possibility. The Sabiti was reportedly 60 miles from the Saudi port of Jeddah when it was hit.  

Foreign Ministry spokesman Abbas Mousavi described the attack as “dangerous adventurism” and warned that the culprits “are responsible for the consequences.”  No country or organization immediately claimed responsibility for the attack, and Iran provided no evidence of a missile strike. The price of Brent crude rose by two percent in response to the news.  

Oct. 12 - Ali Shamkhani, secretary of Iran’s Supreme National Security Council, warned that Tehran would respond to an alleged attack its oil tanker on October 11. “Vicious behavior in international waterways will not go without a response,” Shamkhani said. Saudi Arabia denied involvement and claimed it had a received a message from the ship’s captain “that the front of the vessel has been broken, resulting in an oil spill in the sea from the cargo and tanks of the vessel.”   

Oct. 14 - Iran’s oil ministry released images of the tanker Sabiti, which clearly showed two holes in its hull just above the waterline. President Hassan Rouhani claimed a foreign government was responsible for the October 11 attack, which occurred in the Red Sea some 60 miles away from the Saudi Arabian port of Jeddah. “If a country thinks that it can create instability in the region without getting a response, that would be a sheer mistake,” Rouhani said. 


Oct. 18 - Japan announced it would not join a U.S. maritime coalition to protect merchant shipping in the Persian Gulf. “We won’t join the United States, but will cooperate closely with them,” said Chief Cabinet Secretary Yoshihide Suga. “Self Defense Force assets will ensure the safety of vessels related to Japan.” Tokyo said it would send warships and aircraft to patrol the waters. 

Oct. 21 - Officials from more than 40 countries met in Bahrain to discuss maritime security in the Persian Gulf and efforts to counter Iran’s destabilizing activities in the region. The United States and Poland co-sponsored the two-day meeting, which stemmed from a Middle East conference held in Warsaw in February. "The meeting is an occasion to exchange views on how to deal with the Iranian menace and to guarantee freedom of navigation," said Bahrain’s foreign ministry. 

Oct. 22 - U.S. Defense Secretary Mark Esper said Washington would ask NATO allies to contribute additional resources to protect Saudi Arabia from Iran. Esper specifically urged France, Britain and Germany to contribute more to the Gulf security initiative. He also said Saudi Arabia would “help underwrite” some of the U.S. costs for the additional aid. 

Oct. 31 - Saudi Arabia freed 19 Iranian fishermen held since December and January. The crews of two fishing boats were captured when “bad weather forced the boats into Saudi Arabia’s territorial waters,” according to Tasnim News Agency. The men were released following talks between the two countries. 

Nov. 7 - Britain lowered the threat level for its flagged ships traveling through the Strat of Hormuz. “UK-flagged ships will soon be able to transit the Strait of Hormuz without close Royal Naval accompaniment, following a decrease in the specific risk of detention of these vessels,” said a government spokeswoman. 

Nov. 8 - Iran shot down a “foreign” drone over the port city of Mahshahr in the country’s southwest, according to IRNA state news agency. “The downed drone definitely belonged to a foreign country. Its wreckage has been recovered and is being investigated,” said Khuzestan Province Governor Gholamreza Shariati. Military officials said the drone was destroyed before it could reach “sensitive” centers of the country. 


Dec. 4 - Japan planned to send around 270 sailors to protect Japanese ships transiting the Persian Gulf, according to Nikkei business daily. Tokyo will reportedly deploy one escort ship and one patrol aircraft in a one-year mission that could be renewed annually. Japan’s constitution prevents a standing military but allows for self-defense operations. 

Dec. 10 - Iran’s Navy Commander Rear Admiral Hossein Khanzadi met with Pakistani military officials to discuss increased naval cooperation between the two countries. Pakistan reportedly asked Iran to partake in joint naval drills next month. “Our main approach is to broaden cooperation between Iran and Pakistan at sea and we are pursuing it seriously in various operational, technical and educational areas besides information exchanges,” Khanzadi said. 

Dec. 12 - Saudi Arabian officials said that they hoped to ease tensions with Tehran after a September attack on oil facilities that was blamed on Iran. On December 11, Saudi officials accused the Iran-backed Houthis of firing a projectile at a Saudi hospital near the border city of Jizan. Saudi Arabia and Iran had exchanged messages and communicated through intermediaries in recent months, according to Saudi, European and U.S. officials. Bahram Ghasemi, Iran’s ambassador to Paris, said that Tehran had already presented a peace plan to Riyadh, which included a joint pledge of nonaggression and cooperation. 

Dec. 15 - Iranian Foreign Minister Mohammad Javad Zarif said that discussions between Saudi Arabia and Qatar were good for regional stability. Doha and Riyadh had cut diplomatic ties and trade links in June 2017, following allegations that Qatar backed regional terrorist groups. On December 14, Qatari Foreign Minister Mohammed bin Abdulrahman al Thani reported that there had been “small progress” in talks aimed to resolve the dispute. 

Dec. 17 - Admiral Tony Radakin, Britain’s First Sea Lord, warned that the Iranian threat to shipping in the Persian Gulf “has not gone away.” Radakin called Iran’s seizure of the Stena Impero, a British-flagged tanker, “aggressive” and “outrageous.” He added that Britain would maintain its increased naval presence in the Persian Gulf as part of the U.S.-led maritime coalition, Operation Sentinel. 

Dec. 27 - China, Russia and Iran held joint naval exercises in the Indian Ocean and Gulf of Oman. The four-day drills would cover 17,000 square kilometers and consist of "various tactical exercises," including target practice and rescue operations. "َAmong the objectives of this exercise are improving the security of international maritime trade, countering maritime piracy and terrorism, exchanging information regarding rescue operations and operational and tactical experience," said Iran’s Second Rear Admiral Gholamreza Tahani.


Some of the information in this article was originally published on June 13, 2019.