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PolicyWatch 3327

Iran's Asymmetric Naval Response to 'Maximum Pressure'

Michael Connell, Farzin Nadimi, and John Miller

Also available in العربية فارسی

June 10, 2020

Three veteran observers of Iranian naval forces and doctrines assess the country's ability to punch above its weight in the Persian Gulf.

On May 27, The Washington Institute held a virtual Policy Forum with Michael Connell, Farzin Nadimi, and John Miller. Connell directs the Iranian Studies Program at the Center for Naval Analyses and formerly served as the organization’s field representative to U.S. NAVCENT headquarters in Bahrain. Nadimi is an associate fellow with The Washington Institute and author of its recently updated study Iran’s Evolving Approach to Asymmetric Naval Warfare: Strategy and Capabilities in the Persian Gulf. Miller, a retired vice admiral in the U.S. Navy, most recently served as commander of the Fifth Fleet in Bahrain and head of NAVCENT. The following is a rapporteur’s summary of their remarks.


Recent events, including the harassment of U.S. naval ships by armed Iranian vessels in April, have highlighted the potential for escalation in the Persian Gulf. The April incident was followed by a U.S. Navy warning that any armed vessel approaching within 100 meters of American vessels would be subject to lawful defensive measures. Although hostile interactions between the two countries have occurred in the Gulf for years, these interactions are now playing out against the backdrop of Washington’s “maximum pressure” campaign and its resultant tensions. Both parties have stated that they do not seek conflict; however, the current environment has created a greater chance for escalation and miscalculation.

Iran’s maritime strategy is “make do with less.” Iranian naval forces have invested in capabilities that play to their strengths and target their adversaries’ weaknesses. Such technologies include limpet mines, coastal defense cruise missiles, and small to medium-size submarines.

Geography also provides Iran with a tactical advantage in the Gulf. The confined environment favors offense over defense, allowing for little reaction time, and heavy maritime traffic provides an opportunity to mask operations. Coastal defense cruise missiles are deployed on Iran’s long coastline and on Abu Musa, the Tunbs, and the Farsi islands. Moreover, the terrain on the northern side of the Gulf is rocky, with many inlets playing to Iran’s advantage by enabling guerrilla-like tactics at sea through small-unit ambushes and hit-and-run operations.

Reducing the U.S. naval presence in the Gulf is not a viable solution for preventing escalation because Iran has demonstrated its desire to expand its reach outside the region. It has extended the range and improved the accuracy of its ballistic missiles and unmanned aerial vehicles, and used those capabilities to attack Saudi infrastructure.

Another problematic factor is Iran’s decentralized naval command and control. In 2008, it shifted to a mosaic defense strategy by delegating more authority to lower-echelon naval commanders. This increases the chance of escalation and miscalculation in the Gulf because the Islamic Revolutionary Guard Corps Navy (IRGCN) rewards aggressive, forward-leaning commanders who take risks.


Iran’s naval capabilities are split between the Islamic Republic of Iran Navy (IRIN) and the IRGCN. Since the Iran-Iraq War, both have expanded their capabilities. In 2007, Supreme Leader Ali Khamenei separated the operational areas of the navies: the IRIN was assigned responsibility for the waters outside the Persian Gulf, while the IRGCN was made responsible for the Gulf and the Strait of Hormuz.

In 2009, Khamenei added the prefix “strategic” to the IRIN’s title and gave it a mission to maintain a presence in waters beyond the 10th parallel north (a line extending from the Horn of Africa to the southern tip of India). This expanded mission prompted the navy to initiate a series of projects to build warships domestically in an effort to grow the fleet. However, the IRIN lacks the budget necessary for rapid expansion and struggles with command and control. While retaining good strike capabilities, without the capability to deploy antiship missiles and naval mines, the IRIN is at best capable of protecting Iran’s lines of communication into the Arabian Sea and the Gulf of Aden.

Since the Iran-Iraq War, the IRIN has reached a number of important milestones in terms of expanding its capabilities. These have included delivery of the first Kilo-class submarine in 1991, which provided a new subsurface warfare capability; the commissioning of its first domestically produced warship, the Sina-class fast-attack craft, in 2003; and the commissioning of the first Mowj-class frigate, the Jamaran, in 2010. More recently, the IRIN has developed 4,000- and 7,000-ton warships and 600- and 1,200-ton submarines. Yet it does not have the budget necessary to achieve Tehran’s aspirations for a truly capable blue water navy.

The IRGCN was created out of necessity in 1985 during the Iran-Iraq War. Since then, it has developed from a group of untrained sailors into a capable naval force with significant special operations capabilities, which it demonstrated in summer 2019 by using limpet mines to disrupt shipping in the region. The IRGCN’s domestically produced missiles and speedboats enable it to effectively cover the entire Gulf region.

The IRGCN has reached many milestones of its own. These include introducing the C-802 antiship missile in the early 1990s; adding North Korean Houdong missile boats in 1997; testing the Shkval rocket-propelled torpedo in 2004; gaining responsibility for the Persian Gulf and Strait of Hormuz in 2007; transferring its headquarters from Tehran to Bandar Abbas in 2010; and introducing the Khalij-e Fars antiship guided ballistic missile in 2014.

In recent years, the IRGCN has expanded its unmanned explosive boat capabilities and the number of unmanned aerial vehicles it can use for surveillance and strike missions. It has explosive boats positioned all around the Gulf, but the majority are near the Strait of Hormuz in tunnels that offer cover, concealment, and the ability to launch directly into the waterway. As the maximum pressure campaign continues, Tehran could take an increasingly aggressive stance toward the U.S. presence in the Gulf, thereby increasing the risk of escalation and miscalculation.


Despite harsh sanctions, Iran’s navy has been able to build conventional and asymmetric capabilities to pursue its maritime strategy. Given the strategic importance of the region, Iran’s maritime activity has a significant impact on the Middle East and the global economy.

There are several maritime chokepoints across the globe that play a significant role in the flow of commerce; however, the Bab al-Mandab and the Strait of Hormuz are unique because they are the only two under threat. In the Strait of Hormuz, ships are constantly at risk of detention, harassment, or seizure. Shipping through those straits is governed by international treaties and conventions, specifically the UN Convention on the Law of the Sea. Despite Iranian claims of ownership over the Strait of Hormuz, it is an international waterway.

Iran has developed unique capabilities to advance its strategic objective of applying pressure in the Strait of Hormuz, including ballistic missiles, land/sea-based antiship missiles, mines, submarines, tactical aircraft, air defense systems (e.g., the S-300), fast-attack and in-shore craft, and drones. The country’s indigenous drone program is notably impressive because it has improved capabilities for command and control, over-horizon targeting, and battle damage assessments. The newly acquired S-300 surface-to-air missile was particularly concerning to the United States because it could facilitate the employment of advanced antiship missiles to strike high-value targets in the Gulf and beyond.

There have been numerous close brushes between the United States and Iran in recent years. The decentralized structure of Iran’s navy makes it difficult to assess at what level those operations and attacks were authorized. Given the scope and size of the operation to harass U.S. naval ships in April, it was most likely sanctioned at a high level within the Iranian government. This would follow a consistent pattern: when Iran faces pressure domestically, it responds by using its navy to harass shipping in an effort to raise tensions, create national unity, and deflect attention from other problems. Currently, Iran is facing numerous challenges, including high unemployment, high inflation, crushing sanctions, and COVID-19. The unprofessional and unsafe incidents will continue until the maximum pressure campaign eases.

The subsequent warning issued by the U.S. Navy in May, cautioning mariners to remain 100 meters from U.S. vessels, will have little effect on Iran, which already violates conventional sea laws through its unsafe behavior. The notice also does not take responsibility away from individual commanders, and in some cases individual sailors, who are forced to discern what type of behavior qualifies as a breach of the warning. In many cases, the distance is not as important as the overall posture of the foreign vessels. In a situation where a ship is acting aggressively, the United States has several options before resorting to lethal fire, including bridge-to-bridge communications, flares, and warning shots. However, opportunities for miscalculation will arise every time the Iranian navy decides to engage in such risky behavior.

This summary was prepared by Hannah Coupe. The Policy Forum series is made possible through the generosity of the Florence and Robert Kaufman Family.