Building Maritime Security Coalitions — Lessons Learned from the Strait of Hormuz

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Once a military operation is launched, reflecting on lessons learned can sometimes be an afterthought. Nearly two years after the establishment of separate U.S. and European maritime security coalitions in the Strait of Hormuz, very little exists by way of commentary exploring the policies that shaped these efforts. As two former officials from Washington and Paris who were present at the creation of our respective coalitions, we feel it is important to record some policy lessons that leaders might consider should they want to build future maritime coalitions.

Since the withdrawal of the United States from the Iran nuclear deal in 2018, tensions with Tehran have occasionally escalated in the Strait of Hormuz, the world’s busiest oil shipping lane. After Washington re-imposed sanctions on Iran’s oil exports in May 2019, Iran attacked civilian tankers passing through the Gulf, prompting international concern. Tensions culminated on July 19, 2019 when Iranian authorities seized the British-flagged tanker Stena Impero in Omani waters.



In November 2019, the United States established the International Maritime Security Construct, also known as Operation Sentinel. Today, member nations consist of the United States, the United Kingdom, Albania, Bahrain, Estonia, Lithuania, Saudi Arabia, and the United Arab Emirates. Reluctant to join the U.S.-led coalition because of its connection to the “maximum pressure” approach advocated by the Trump administration toward Iran, European countries instead agreed on a distinct maritime initiative. Called European Maritime Awareness in the Strait of Hormuz, or Operation Agenor, this coalition was formally launched in January 2020 by eight European nations: Belgium, Denmark, France, Germany, Greece, Italy, the Netherlands, and Portugal.

Through the deployment of naval assets, both coalitions have aimed to provide reassurance to merchant shipping and deter further attacks. While the coalitions are still ongoing, initial lessons can be learned. As the international security environment grows more and more volatile, building successful security coalitions will be paramount not only for Europeans but also for the United States, which will increasingly need to rely on its partners to help to defend its national security interests.

Lesson 1: Political Objectives Should Be Consistent and Clearly Defined

Coherent messaging and clear objectives are paramount to the success of a maritime coalition. They ensure that participating nations understand the scope of their involvement and guarantee that adversaries cannot exploit contradictions in messaging and objectives. At its inception, the American-led coalition proved to be controversial not because of its mission — stability in international waterways is a shared goal of most nations — but because of its political framing. Most countries feared that participating in the U.S.-backed coalition would invariably make them complicit in the Trump administration’s “maximum pressure” campaign and thus a ripe target for the Iranian military.

State Department and Defense Department officials initially marketed the American-led effort as a general attempt to increase “maritime domain awareness.” As a top Defense Department official indicated in July 2019, Operation Sentinel was a surveillance mission to expose all types of malign activities, “not a coalition against Iran.” Yet, just weeks later, the defense secretary himself suggested that Iran was the primary focus, stating explicitly that deterring Iran was among the top priorities for the initiative. Secretary of State Mike Pompeo confirmed in January 2020 that the military had a distinct role in the maximum pressure strategy, alluding in part to the US.-led maritime efforts.

Even as some countries may have been close to contributing, their fear of being drawn into a conflict between the United States and Iran proved to be a risk that outweighed any potential gain. By making a connection to the maximum pressure policy, the U.S. messaging led most Europeans (with the notable exception of the United Kingdom) to go their own way. Opposed to any diplomatic or operational move that would further destabilize the region, the Europeans carefully presented their maritime initiative as not targeting any specific country. The political statement establishing the European maritime initiative notably mentions the “risk of a potential large-scale conflict” and calls for “enhanced de-escalation initiatives.”

This lack of shared diplomatic objectives made a joint transatlantic approach impossible despite similar economic and security interests. This first lesson learned is of particular importance for Washington, as Europeans’ confidence towards the United States has dramatically eroded over recent years. If the U.S. administration wants to convince its European partners to engage in future combined operations, Washington will need to double down on its diplomatic efforts to ensure a transatlantic alignment beforehand.

Lesson 2: Legal Authorities and Political Mandates Should Be Clear

A clear legal framework is also critical for any successful maritime security coalition. Rules of engagement need to be well-defined, such as whether self-defense is to be exercised collectively or whether each nation’s forces may only defend themselves. In the case of the Strait of Hormuz, both the United States and the Europeans decided to give sufficient security guarantees to convince countries to join without imposing a collective security arrangement. Collective action beyond coordination and information-sharing fall outside the mandate of the coalitions. In other words, if another nation’s military or commercial vessel were attacked, participating nations would seek to expose the attack but would not be expected to assist the distressed ship unless authorized by their own government. This flexibility proved essential to convince some countries who feared getting entangled in a U.S.-Iranian conflict if tensions were to escalate.

Alternatively, other existing maritime security coalitions — such as those conducting counterproliferation activities like Combined Task Force-150 or counter-piracy operations such as operation ATALANTA — have authorities allowing them to conduct activities beyond simply surveillance. For example, participating nations in these coalitions are authorized to interdict, consensually board, and seize vessels suspected of carrying illicit weapons or sanctioned goods, or of taking part in piracy. In those cases, member nations operate under a law enforcement framework rather than a military one. This allows them to use force in the event of an imminent threat to the lives or safety of the boarding party.

A pragmatic approach is also key regarding the political mandate underpinning the coalitions. Both coalitions in the Strait of Hormuz are ad hoc initiatives based on non-binding political declarations. Admittedly, this was possible because both operations only implied de-escalatory presence, and therefore did not require a formal mandate from the U.N. Security Council or, in most cases, national parliamentary approval. Operations Sentinel and Agenor are coalitions of the willing and do not fall under the umbrella of an international organization like the United Nations, NATO, or the European Union. For the Europeans, this flexibility proved essential in swiftly launching the maritime mission. This also ensured the involvement of European countries not participating in the European Union’s defense policy, such as Denmark. Europeans are likely to further explore similar pragmatic solutions to quickly respond to maritime security challenges. As recently experienced in the Gulf of Guinea and soon in the Indo-Pacific, Europeans are establishing a coordinated maritime presence instead of formally launching an E.U. operation.

Lesson 3: Consider Sustainability of Forces in Resource-Strapped Environments

Ideally, maritime coalitions should consist of countries which have the right mix of capabilities. In the case of Operation Sentinel, capabilities skew heavily toward the United States and the United Kingdom, who both bear the greatest weight in more-capable “sentinels.” These “sentinels” have consisted of large military vessels and, in some cases, helicopters that assist in exposing malign activity. Some smaller member nations, such as Albania, only provide personnel while others provide less-capable “sentries” — small patrol craft and corvettes. While all play a role in the coalition’s operations to expose illicit behavior in important waterways, U.S. capabilities probably provide the major contributions for exposing activities, which includes over 2,000 hours of monthly coverage by manned and unmanned surveillance assets.

Sustainability of forces has been a central challenge for the European-led maritime coalition. Even though the coalition is politically supported by eight European countries, in reality only three of them have provided critical capabilities. France has played a leading role by hosting the headquarters in its naval base in Abu Dhabi and by deploying a frigate and surveillance aircraft on a near-permanent basis. The Netherlands and Denmark have also deployed naval assets, while other nations such as Belgium and Greece have occasionally delivered associated support to the mission. Germany has declined to contribute to the mission mainly because of the German law that requires a formal E.U., NATO, or U.N. mandate for any German participation to an international operation. Since Operation Agenor commenced, the coalition has managed to conduct 100 flights, spend 400 days at sea, reassure more than 20 merchant ships, and transit the Strait of Hormuz over 100 times. As things stand, the coalition is therefore able to perform its mission of reassurance at sea. The force generation process nonetheless remains a challenge and existing European assets would certainly not be enough if tensions were to rise. This situation reveals the need for Europeans to act collectively to harness the full potential of their limited naval assets after decades of cuts in defense budgets.

Lesson 4: Embrace a Whole-of-Government Approach

Finally, maritime security coalitions should be closely monitored at the political level to ensure that national governments have a higher-level — and not just military — avenue to address concerns, evaluate milestones, and eventually determine when to stand down. At present, the U.S.-led coalition does not have such a political track, although U.S. diplomats and civilian policy officials were instrumental in building support within partner countries for contributions. While member nations do meet from time to time, these meetings are at the senior military level and not at the political level. Appointing a senior civilian official responsible for Operation Sentinel’s political affairs would have given member nations an appropriate forum in which to discuss the future of the coalition.

By contrast, the European maritime surveillance mission has consistently been part of a wider diplomatic effort led by Europeans to promote regional stability. Participating nations established a political-military contact group composed of senior officials. This steering body helped the Europeans to regularly discuss the progress made by the mission and exchange thoughts on the next steps. Similarly, the Europeans appointed a senior civilian representative for their coalition, now a Danish senior diplomat, to engage with regional countries and partners on maritime security issues with a view to identifying confidence-building measures. Even though this diplomatic track has faced many stumbling blocks due to persistent tensions in the Gulf, this effort was nonetheless necessary to encourage an inclusive regional dialogue on maritime security.


On issues ranging from humanitarian assistance and disaster relief to counter-piracy, maritime trade protection, and freedom of navigation operations, maritime coalitions will continue to be critical for international security. Given the limited naval assets of the United States and its European and Asian partners, maritime coalitions will be increasingly necessary to face a deteriorating security environment from the Mediterranean Sea to the Indo-Pacific.

The lessons learned from the Strait of Hormuz security efforts can serve as a useful framework for future maritime coalitions. As experienced by the U.S.- and European-led endeavors, any successful maritime coalition requires shared diplomatic goals, consistent messaging, clear and flexible legal authorities and political mandates, sustainable and complementary resources, and a credible political framework.

Having these lessons in mind will be critical for the Biden administration, which has put alliances at the forefront of its foreign policy strategy. As underlined by President Joe Biden at the Munich Security Conference, Washington will seek to “revitalize America’s networks of alliances and partnerships that have made the world safer for people.” Achieving this goal will require looking back at the successes and setbacks of past or ongoing U.S.-led coalitions. The Strait of Hormuz is a noteworthy case study in that regard.



Edgar Tam is a visiting fellow based in Paris with the German Marshall Fund of the United States and a former Iran country director in the Office of the Secretary of Defense. The views expressed here are his own and do not represent the Department of Defense.  

Pierre Morcos is a visiting fellow with the Europe, Russia, and Eurasia Program at the Center for Strategic and International Studies and former deputy head of the Strategic Affairs and Cybersecurity Division in the French foreign service. The views expressed here are solely his own. You can find him on Twitter at @morcos_pierre.

Image: U.S. Navy (Photo by Mass Communication Spc. 2nd Class Brandon Woods)