Iran Behind Oil Tanker Attack

On July 29, an oil tanker with ties to Israel was hit in a drone strike off the coast of Oman, killing two crew members. The Mercer Street was owned by a Japanese company and flew the Liberian flag, but was managed by Zodiac Maritime, a company headed by an Israeli shipping magnate. On August 1, U.S., British and Israeli officials charged that Iran was behind the attack. Iran denied involvement. Since 2019, Israel and Iran have reportedly engaged in tit-for-tat attacks on ships owned by or linked to each other. The strike on the Mercer Street was reportedly the first fatal attack.

The attack threatened to increase tensions between Western powers and Iran during diplomacy to restore full U.S. and Iranian compliance with the 2015 nuclear deal. From April to June 2021, Iran and the world’s six major powers—Britain, China, France, Germany, Russia and the United States—held six rounds of talks in Vienna hosted by the European Union. Iran said that it would not resume talks until after Ebrahim Raisi’s inauguration as president on August 5.

The Mercer Street was the second vessel connected to Zodiac Maritime to be attacked in a month. On July 3, the CSAV Tyndall, previously owned by Zodiac Maritime, was struck by either a missile or a drone in the Indian Ocean while sailing from Saudi Arabia to the United Arab Emirates. No one was hurt, but the ship suffered minor damage. Israeli security officials reportedly tied Iran to the attack.


The Attack

During the day, one drone flew toward the Mercer Street but fell short into the water, a U.S. official citing the Mercer Street’s crew told CNN. At night, a second drone hit the ship and blasted a hole in the top of its bridge, a U.S. official told The Associated Press. The captain, a Romanian, and a security guard, a British national, were reportedly killed.

U.S. naval forces from the 5th Fleet, which is based in Bahrain, responded to the ship’s distress call. The tanker was then escorted to a safe port by the aircraft carrier USS Ronald Reagan and the guided missile destroyer USS Mitscher. Oman also deployed jets and a ship to the location of the attack.

Zodiac Maritime said that the Mercer Street was hit while traveling from Dar es Salaam, Tanzania, to Fujairah, the United Arab Emirates. The ship was not carrying any cargo.


International Response

In a statement, Secretary of State Blinken charged that the attack “follows a pattern of attacks and other belligerent behavior” by Iran. There was “no justification, he said, adding that the United States was working with its partners on an “appropriate response.”

British Prime Minister Boris Johnson condemned the attack. “Iran should face up to the consequences,” he told reporters on August 2. “This was clearly an unacceptable and outrageous attack on commercial shipping.” Britain’s Foreign, Commonwealth & Development Office summoned Iran’s ambassador in London in response to the attack. Foreign Secretary Dominic claimed that the attack was “deliberate, targeted, and a clear violation of international law by Iran.” He also reported that Britain was working with allies on a concerted response to “this unacceptable attack.”

Israeli Prime Minister Naftali Bennet called on the international community to “make it clear to the Iranian regime that they have made a serious mistake. In any case, we know how to send a message to Iran in our own way,” he said during a cabinet meeting on August 1. Israel warned that the attack more broadly threatened freedom of navigation. “Iran is not just an Israeli problem, but an exporter of terrorism, destruction and instability that are hurting us all,” Foreign Minister Yair Lapid tweeted on July 30. “I am in constant contact with British Foreign Secretary Dominic Raab, I mentioned to him tonight the need to respond severely to the attack on the ship in which a British citizen was killed.”

Romania’s foreign minister held Iran responsible for the strike. “There is no justification whatsoever for deliberately attacking civilians,” Bogdan Aurescu said in a statement on Aug. 2. Romania’s foreign ministry reportedly summoned the Iranian ambassador in Bucharest to account for the incident.

On August 6, the G7— Britain, Canada, France, Germany, Italy, Japan, and the United States—condemned the attack. “Iran’s behavior, alongside its support to proxy forces and non-state armed actors, threatens international peace and security,” the foreign ministers said in a joint statement. “We call on Iran to stop all activities inconsistent with relevant U.N. Security Council resolutions, and call on all parties to play a constructive role in fostering regional stability and peace.”


Iranian Denial

Iran dismissed the international accusations. “It’s not the first time that the Zionist regime occupying Jerusalem has made such empty accusations against the Islamic Republic of Iran,” Foreign Ministry Spokesperson Saeed Khatibzadeh said on August 1. “Wherever this regime has gone, it has taken instability, terror and violence with it.”

Khatibzadeh challenged Britain and the United States to provide evidence to “support their baseless claims.” On August 2, he also warned that Iran would “decisively respond to any possible adventurism” in response to the alleged tanker attack. Iran’s foreign ministry summoned Britain’s chargé d'affaires, the top diplomat in Tehran, to condemn the British allegations. The ministry also summoned the Romanian ambassador.


Shadow War at Sea

Since 2019, Iran has reportedly targeted at least three Israeli ships. Israel has also accused Iran of attacking tankers owned by third countries, including Japan, Norway, Saudi Arabia and the United Arab Emirates. Over the same period, Israel has sabotaged at least 10 ships—and potentially more than 20—carrying Iranian cargo or oil, The New York Times reported in March 2021. The first well-publicized incident in the maritime conflict between Israel and Iran was the suspicious breakdown of an Iranian oil tanker in the Red Sea in May 2019. The following is a timeline of maritime attacks that reportedly involved Israel and Iran.



May 2 An Iranian tanker, the Happiness I, broke down in the Red Sea. Iran said that the vessel, which was carrying more than one million barrels of oil, malfunctioned when water leaked into the engine room. None of the crew were injured. The tanker was forced to dock in Jeddah, Saudi Arabia. No country claimed responsibility.

Oct. 11 – An Iranian tanker, the Sabiti, was reportedly hit by two missiles in the Red Sea. An Iranian lawmaker, Abolfazl Hassan Beigi, blamed Israel, the United States and Saudi Arabia for the attack, which left two large holes in the ship’s hull above the waterline. The National Iranian Tanker Company said that some oil spilled into the water.  



May 9 – A cyberattack hit computers that regulate maritime traffic at Shahid Rajaee port on Iran's southern coast in the Persian Gulf. The disruption created a traffic jam of ships that waited days to dock. Iran acknowledged that it had been hit by a foreign hack. Israel was reportedly behind the cyberattack, although it did not claim responsibility, according to The Washington Post.



Feb. 26 – The Israeli-owned Helios Ray cargo ship, which flies a Bahamian flag, was damaged by two limpet mines in the Gulf of Oman. Israeli Prime Minister Benjamin Netanyahu blamed Iran for the attack but did not provide specifics. “Iran is the greatest enemy of Israel, I am determined to halt it. We are hitting it in the entire region,” he said on March 1. Tehran denied responsibility. Israel is “playing the victim to distract attention away from all its destabilizing acts and malign practices across the region,” Ambassador Majid Takht Ravanchi said in a letter to the U.N. Security Council on March 9.


March 10 – An Iranian container ship, the Shahr-e Kord, was hit by an explosive object in international waters – about 50 miles off the Israeli coast and reportedly heading for the Syrian port of Latakia – in the eastern Mediterranean. It caused a small fire but no casualties. Iran blamed Israel for the attack because of the geographical location and the way the ship was targeted. The shipping company claimed that the Shahr-e Kord was bound for Europe.

March 25 – The LORI, an Israeli-owned cargo ship that flies a Liberian flag, was struck by a missile in the Arabian Sea. The damage was minimal, and the LORI continued to its final destination in India. A senior Israeli defense official claimed that the IRGC had fired the missile.

April 6 – An Iranian ship, the Saviz, was damaged by a mine planted on its hull in the Red Sea near Djibouti. The vessel had been floating off the coast of Yemen for several years. Iran claimed that the ship was involved in anti-piracy operation. But the Saviz was an armory ship used as a covert “forward base” by the Revolutionary Guards near the strategic Bab el Mandab straits, the U.S. Naval Institute reported in October 2020. Israel reportedly conducted the attack in retaliation for previous Iranian strikes, according to The New York Times.


April 13 – The Hyperion Ray, an Israeli-owned cargo ship that flew the Bahamian flag, was struck by a missile or an unmanned drone near the Fujairah port in the United Arab Emirates. There were no casualties, and the ship continued on its route. The ship was attacked two days after Israel allegedly sabotaged the Natanz nuclear enrichment facility. Iranian Foreign Minister Javad Zarif had vowed “revenge” on Israel.

July 3 – The CSAV Tyndall, a formerly Israeli-owned cargo ship that flew the Liberian flag, was struck by either a missile or an unmanned drone in the Indian Ocean while sailing from Jeddah, Saudi Arabia, to the United Arab Emirates. There were no casualties, but the ship suffered minor damage. Israeli security officials believed that Iran was responsible for the attack, Haaretz reported. The ship had previously been owned by Israeli billionaire Eyal Ofer but was sold months ago, the Times of Israel reported. The vessel's owner at the time of the attack was Polar 5 LTD, a London-based shipping company.

July 26 – The Revolutionary Guards researched how to hack water filtration and ballast systems to sink cargo ships, Sky News reported. "These pumps are used to bring water into the tanks through centrifuges and in order to operate correctly, the task must be completed with precision," one report read. "Any problems could result in the sinking of the ship." The documents "seem to indicate how cyber capabilities can be put to use in the maritime conflict between Israel and Iran," Haaretz reported

July 29 – The Mercer Street—an oil tanker owned by a Japanese company that flew the Liberian flag but was managed by Zodiac Maritime, which is headed by an Israeli shipping magnate—was attacked off the coast of Oman. Israeli officials told The New York Times that multiple Iranian drones were involved in the attack. Two crew members, one British national and one Romanian national, were reportedly killed. “Iran is not just an Israeli problem, but an exporter of terrorism, destruction and instability that are hurting us all,” Israeli Foreign Minister Yair Lapid tweeted. On August 1, U.S., British and Israeli officials charged that Iran was behind the attack.

Iran denied involvement. But Iranian state media reported that the attack on the tanker was in response to an alleged Israeli attack on al Dabaa airport in Syria. Al Alam News Network cited “informed sources in the region.” It did not specify who attacked the Mercer Street.

Aug. 6 – U.S. Central Command released the findings of its investigation into the Mercer Street drone attack and published photos of debris recovered from the tanker. Forensic analysis confirmed that the drone components were identical to Iranian unmanned aerial vehicles (UAVs) and that it was loaded with explosives.

Aug. 25 – Israel claimed that the drone used to attack the Mercer Street was "launched from Iranian territory and approved by the Iranian leadership." Israeli Defense Minister Benny Gantz briefed foreign diplomats in Jerusalem on the drone attack, as well as Iran's doubling of military spending over the past five years.



Garrett Nada, managing editor of The Iran Primer at the U.S. Institute of Peace, assembled this report. Julia Broomer, a research assistant at the Woodrow Wilson Center, contributed to an earlier version of the timeline. 

Some of the information in this article was originally published on August 2, 2021.