U.S. Mobilizes Maritime Coalition in Persian Gulf

On July 19, the United States announced plans to mobilize an international maritime force to protect vital shipping routes in the Persian Gulf. The Pentagon said the mission would be “to increase surveillance of and security in key waterways in the Middle East to ensure freedom of navigation” in the Gulf, through which roughly one fifth of the world’s oil passes. The U.S. move followed attacks on six foreign tankers between May and June outside the Strait of Hormuz in the Gulf of Oman and Iran’s shooting down of a U.S. drone near its coast. Operation Sentinel will escort flagged vessels of participating nations in coordination with European, Asian, and Middle Eastern allies. The following countries have committed to work alongside or collaborate with the U.S.-led maritime mission: Australia, Bahrain, Britain, Israel, Saudi Arabia, and the United Arab Emirates. The following is a timeline of developments.

July 19 - 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. 

July 23 - 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 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.

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. 4 – 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 – 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. 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. 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 - 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.

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. Emirati Foreign Ministry official Salem al Zaabi said the UAE would join the coalition to "ensure global energy security and the continued flow of energy supplies to the global economy."