Iran’s New Naval Ambitions

Since the start of the war in the Gaza Strip in October, the Red Sea has become a second battleground. The Houthis, an armed group based in Yemen and backed by Iran, have launched missiles and sent armed drones to strike commercial ships passing through the maritime route. They have sunk two vessels and damaged dozens more. By disrupting the route through which at least 12 percent of all international trade passes in a typical year, the Houthis’ attacks have caused shipping costs to skyrocket and upended the trade system. The group has pledged to continue targeting merchant vessels until Israel ends its military operations in Gaza, calculating that the disarray it causes will increase the international pressure on the Israeli government to bring the war to a close.

The Houthis may be leading this attack, but they are not acting alone. The group is a part of Iran’s “axis of resistance,” a network of mostly nonstate partners that Tehran mobilizes in service of its regional goals. Iran has provided weapons and intelligence to support the Houthis’ Red Sea campaign, and the country’s leaders have endorsed the strikes on commercial ships.

For Iran, assisting the Houthis’ attacks is just one part of a broader strategic shift—one that increasingly relies on maritime capabilities to keep Iran’s enemies on the back foot. Until around four years ago, Iran’s activities at sea were largely confined to several hundred Islamic Revolutionary Guard Corps (IRGC) speedboats patrolling in the Persian Gulf and periodic threats to close the Strait of Hormuz, a crucial chokepoint for global oil shipments. Lately, however, Iran’s naval forces have acquired more advanced vessels, including new submarines and missile-armed warships, and have begun to venture as far as the Atlantic and Pacific Oceans. These changes are in line with Iran’s “forward defense” doctrine, adopted after the Iran-Iraq War in 1988 and consolidated in the early 2000s, which aims to engage adversaries far from Iran’s borders before they can pose a threat to the homeland.

Iran’s revamped navy is now at the heart of its military strategy. The tools that have long been central to Iran’s forward defense on land—missiles, drones, and proxy militias—are today being deployed at sea. To further bolster its power, Tehran has forged naval partnerships with China and Russia. By enhancing its maritime presence, Iran aims not just to deter attacks by foreign actors that may wish it harm but to do so by directly threatening those adversaries—primarily the United States.

Iran’s maritime threat demands a response. Washington must reduce the vulnerability of the international shipping system by developing alternative trade routes, and it can reduce Tehran’s desire to disrupt maritime transit in the first place by allowing Iran to integrate into the global trade system in limited ways. In addition, as the United States’ partners in the Gulf improve their relations with Iran, Washington should encourage them to wield their influence to rein in the country’s provocations. And on the military front, the United States must work closely with its allies to counter and contain Iranian naval power.

FORWARD DEFENSE

Iran has introduced several notable changes as it develops its naval strategy. First, the IRGC Navy has assumed a dominant role. The IRGC Navy historically comprised a fleet of agile speedboats that harassed American ships in the Persian Gulf and the Strait of Hormuz. Meanwhile, Iran’s conventional naval forces with larger vessels patrolled, undertook antipiracy operations, and gathered intelligence in more distant waters—essentially defensive missions. The disparity in the two navies’ capabilities effectively disappeared in January, however, when the IRGC Navy received two new advanced warships. It is expected to acquire more in the coming years. The vessels will allow the IRGC Navy to conduct operations beyond the Persian Gulf and beyond the scope of the conventional naval forces’ mission. In 2020, Supreme Leader Ali Khamenei specifically tasked the IRGC with expanding Iran’s ability to reach adversaries in distant waters, in keeping with a strategy known as the “long hand.”

The new forces’ technological capacity is another prominent change. Iran has been developing its missile program for decades, but now it is increasingly arming its naval fleet with the latest technology. The IRGC Navy’s warships are equipped with advanced missile systems that have a range of up to 430 miles. Previously, Iran’s land-based missiles could reach targets within only 1,200 miles of Iranian territory. But the mobility of a maritime fleet vastly expands the scope of potential targets.

Over the past few months, Iran has conducted naval missions to assist members of the axis of resistance with increasing frequency. According to a report in The Telegraph, a unit in the IRGC’s Quds Force—an elite force of the organization tasked with extraterritorial operations—has sent weapons to Hezbollah by stowing them on cargo ships that depart from the Iranian port city of Bandar Abbas. The ships make a stop at Syria’s Latakia port, where the weapons are unloaded, before continuing their commercial routes. Iran has also employed “ghost tankers”—vessels that turn off their tracking systems and change their names and registration to evade detection—to deliver oil to Syria, where Syrian President Bashar al-Assad maintains a close alliance with Tehran and is considered a crucial member of the axis of resistance. And in the Red Sea, the Iranian ship Behshad has been providing intelligence and surveillance support for the Houthis’ attacks on international shipping.

Iran increasingly relies on maritime capabilities to keep its enemies on the back foot.

Another key component of Iran’s maritime activities is tightening the country’s control of strategic waterways. Iran’s own geography gives its naval forces access to the Persian Gulf and the Strait of Hormuz, through which more than 20 percent of the oil consumed globally is shipped. Its partnership with the Houthis extends its reach to the Bab el Mandeb Strait, the passage between Yemen and the Horn of Africa at the southern opening of the Red Sea. In 2018, Iranian President Hassan Rouhani implied that Iran held sway in Bab el Mandeb when he said, “We have many straits, the Strait of Hormuz is just one of those.” Fast-forward five years to the Houthis’ attacks on ships passing through this waterway and Rouhani’s words read like a warning. State-affiliated media in Iran have reported that Tehran has sent Iranian-made antiship ballistic missiles to the Houthis and that Iranian technology has helped the Houthis strike ships in the Red Sea. It is possible that Iran has transferred similar missile technology to Hezbollah, which is already believed to possess Russian-made antiship missiles. Combining the coastal positions and maritime capabilities of axis of resistance members with its own, Iran can project power beyond the Persian Gulf to the Red Sea and the eastern Mediterranean.

Partnerships with China and Russia constitute the final pillar of Iran’s maritime strategy. Since 2019, the three countries have conducted four joint naval exercises, most recently in the Gulf of Oman in March. This display sent a signal of their capability and intent to challenge Western naval dominance in the region. As part of Iran and Russia’s growing military collaboration since the start of the war in Ukraine, Iran has also sought Russian assistance in developing more advanced long- and medium-range naval precision missiles.

THE LURE OF THE SEA

Iran’s revamped maritime strategy is primarily a response to changes in the country’s security environment. For one, Tehran sees a need to diversify its options for pushing back against the United States. Previously, U.S. military bases in Gulf countries offered easy targets; when diplomatic tensions escalated and Washington intensified its pressure on Tehran, Iran could threaten to strike a U.S. base. But over the past two years, Iran has taken steps to reconcile with its Arab neighbors, and it is now more reluctant to jeopardize those ties. Tehran’s threats against U.S. bases in the region have significantly decreased as a result. In a telling example of Iran’s caution, prior to its large-scale missile and drone attack on Israel in April, Iran informed several Gulf countries of its plans to reassure them that the operation would be confined to Israel and would not expand into their territories.

To avoid potentially angering its neighbors, Iran has begun to focus its threats on American interests farther afield. In May, for example, IRGC Navy Commander Ali Reza Tangsiri announced that one of the force’s new missile-equipped warships had sailed past Diego Garcia, a remote island in the Indian Ocean where U.S. military personnel are stationed. The maneuver was a clear message to the United States that Iran’s naval fleet is expanding its reach.

Iran’s new strategy also aims to box in Israel. Iranian proxies and allied militias in Lebanon and Syria already pose a military threat along Israel’s borders, and by providing Hezbollah and the Houthis with drones and antiship missiles, Iran is giving its partners the means to impose significant costs on Israel by targeting its shipping and ports. In a potential conflict, Iranian-backed groups could strike Israeli targets both on land and at sea. The United States could also have more difficulty providing aid and logistical support to Israel, as its own ships would be vulnerable to Iranian and allied attacks. Just establishing these capabilities enhances Iran’s leverage over Israel, which now has to factor in the risk of fending off attacks on multiple fronts into its own strategic planning.

Some of Tehran’s motivations are defensive. Iran seeks to use its maritime presence to raise the costs of a conflict for its adversaries, whether Israel, the United States, or another hostile power. It can do this by honing its ability to impede international transit routes, as the Houthis have done during the war in Gaza. To build this capability further, Iran has attempted, albeit unsuccessfully, to establish a naval base on Sudan’s Red Sea coast in exchange for providing advanced weaponry to the Sudanese Armed Forces. Together with its influence over the Houthis, a base in Sudan would give Iran access to a maritime chokepoint from two directions. In Tehran’s calculation, if its enemies were assured that a regional skirmish would upend global trade, they would be less likely to risk economic chaos by clashing with Iranian forces or launching an attack on Iranian soil.

Finally, operating by sea has become more attractive, as Israeli surveillance has made it increasingly difficult for Iran to smuggle weapons to its allies by land and air. Traditional routes—such as the “land bridge” that connects Iran to Syria and Lebanon through Iraq and the “air corridor” that links Iran to Syria via Iraq—have grown perilous as Israeli intelligence operations identify these transports and Israeli airstrikes disrupt them. Maritime transport, by contrast, is less heavily monitored and offers more flexibility in terms of altering routes and using different kinds of vessels, allowing Iran to maintain a steady flow of arms to its allies.

REDUCING THE THREAT

Even as Iran reorients its maritime strategy, the country’s conventional naval power still lags far behind that of the United States and most of its allies. But that does not mean Iranian activities at sea do not pose a threat. The real danger is Tehran’s growing capability to wage asymmetric warfare in maritime domains, using a combination of missile and drone attacks, operations through proxy militias, and control over strategic waterways to target U.S. interests.

Iran’s deepening ties with China and Russia heighten the threat. Not only could Tehran gain advanced naval technologies and experience conducting effective naval warfare through these partnerships, but each country’s maritime activities, whether organized in concert or not, could also serve their shared goal of challenging U.S. dominance at sea. As shown by the failure of the U.S.- and British-led military campaign to stop the Houthis’ strikes on ships in the Red Sea, asymmetric naval operations are difficult to combat, especially when they take place in distant waters. If Iran, China, and Russia were to direct maritime attacks on U.S. naval assets and commercial shipping all at the same time and across multiple geographic areas, they could overwhelm U.S. naval forces.

The United States must take action to mitigate the Iranian maritime threat. By advancing diplomatic initiatives to develop alternative international transit routes, Washington and its partners can reduce their dependency on vulnerable passages. One such initiative is the India–Middle East–Europe corridor. The United States should marshal the actors involved—including India, Israel, Saudi Arabia, the United Arab Emirates, and the European Union—to secure funding, set concrete milestones, and expedite the construction of railways, ports, and other critical infrastructure. Washington can also move the economic project forward by encouraging American companies to invest through public-private partnerships. In a similar vein, the United States can lend its support to the Development Road project, which will connect the Persian Gulf to Turkey and Europe via Iraq. Washington can help this venture along by assisting the Iraqi government in its efforts to enhance security along the route and by fostering closer cooperation between Baghdad and Ankara. The United States can also help Iraq secure loans or grants for the project through the International Monetary Fund and the World Bank.

Tehran sees a need to diversify its options for pushing back against the United States.

Furthermore, Washington can encourage its partners in the Gulf to use their warming relations with Tehran to reduce the risk of maritime conflicts. Both Iran and the members of the Gulf Cooperation Council have articulated their interest in regional security, and the next step is for them to develop a framework that contains assurances that all parties will respect international trade and shipping in the Persian Gulf and the Strait of Hormuz. A nonaggression pact between Iran and its neighbors could be the first step toward a regional security framework, as it would foster trust and lower the chances of clashes at sea. The United States needs to make clear to its partners that it supports such negotiations.

The Biden administration should also try to integrate Iran into the global economy, albeit in limited ways. U.S.-led sanctions have restricted the country’s international trade, which leaves Tehran with less to lose by obstructing transit routes. Raising the cost of disrupting global trade for Iran could help change its calculations. One step Washington can take in this direction is to renew a sanctions waiver that would allow India to proceed with its plans for the development and management of the Iranian port of Chabahar.

Along with its diplomatic efforts, the United States should urge its regional partners to take military measures to contain Iran’s maritime challenge. Arab-Israeli normalization talks offer an opportunity to secure such commitments. A formal military coalition that included Israel, Saudi Arabia, and the Gulf states would no doubt provoke Iran, but these talks are more likely to yield narrower forms of cooperation, such as provisions for regular maritime intelligence sharing and technical and logistical support. These efforts would be particularly significant if a regional maritime security agreement that included Tehran failed to materialize. In that scenario, the Gulf states would seek other ways of restraining Iran’s power at sea, including military cooperation with the United States.

Collaboration with Washington’s European allies is equally important. European forces have joined the campaign against the Houthis in the Red Sea, but their ability to deploy rapidly and to sustain operations far from their home bases is limited. To equip their militaries to respond quickly to asymmetric naval threats in the future, European governments must increase the number of forward-deployed vessels in their fleets and improve logistical support.

As Iran’s maritime forward defense takes shape, the United States and its allies need to be prepared. Iran’s strategy is designed to be nimble, allowing it to raise the stakes of regional conflict and to threaten U.S. interests in many places at once. Washington will need to draw on the full range of its diplomatic and military tools in order to deny Tehran the advantage it seeks at sea.