United States Institute of Peace

The Iran Primer

Gulf III: Iran’s Power in the Sea Lanes

Michael Connell

What is the record of interaction between the U.S. and Iranian navies in the Persian Gulf?
            The United States and Iran have never officially been at war, but several recent incidents between the U.S. and Iranian navies have had the potential to escalate into armed confrontations. In January 2012, three Revolutionary Guards speed boats harassed the USS New Orleans. The small craft came within 500 yards of the amphibious transport ship as it was transiting the Strait of Hormuz. On the same day, Iranian small boats also harassed the U.S. Coast Guard Cutter Adak, operating east of Kuwait City.
      Most of the close encounters involved the naval arm of the Islamic Revolutionary Guard Corps (IRGC), which is distinct from the conventional Iranian Navy. In contrast, U.S. Navy commanders routinely say their interactions with the regular Iranian Navy are professional.
      The U.S. and Iranian navies had several hostile encounters in the 1980s. Iranian attacks on commercial shipping in the Persian Gulf triggered armed exchanges between their navies during the Iran-Iraq War (1980-1988). The United States responded in Operations Nimble Archer (October 1987) and Praying Mantis (April 1988).
What types of situations could spark a larger conflict?
            The United States and Iran are unlikely to initiate hostilities in the Gulf waters without provocation. But a minor incident between the U.S. and Iranian navies could flare into a major encounter. The other main danger is an Israeli strike on Iran’s nuclear sites, which could pull the United States into a wider conflict.
            If Israel strikes, the Iranians have pledged to retaliate by attacking U.S. forces in the region. Whether they would actually do so is debatable. The Iranians could simply be posturing to deter Israel and the United States. Regardless, the United States is likely to maintain a robust presence in the region to deter an Iranian attack or — should that fail — to respond militarily.
How might such a conflict be diffused?
            Various options have been proposed that could mitigate the danger of an unintended escalation after a maritime incident in the Gulf, beyond routine bridge-to-bridge communications. These include:
· Creation of common “rules of the road” to govern interactions between the U.S. and Iranian navies, something akin to the Incident at Sea (INCSEA) arrangement that the U.S. and Soviet navies had during the Cold War,
· Establishing a direct hotline between U.S. and Iranian commanders in the Gulf. In late 2011, military officials in Washington broached this idea, but Iranian regular and IRGC Navy commanders rejected it.
How are Iran’s naval forces deployed in the Gulf?
            Iran has two independent naval forces with parallel chains of command. The conventional navy is called the Islamic Republic of Iran Navy (IRIN). The second is the naval wing of the Revolutionary Guards (IRGCN). The two navies have overlapping functions and areas of responsibility, but they are distinct in terms of how they are trained and equipped— and more importantly also in how they fight.
      The backbone of the regular navy’s inventory consists of larger surface ships, including frigates and corvettes, and submarines. With its longer range surface assets, the IRIN is generally considered to be a conventional “green water” navy. It operates at a regional level, mainly in the Persian Gulf and Gulf of Oman but also as far afield as the Red Sea and the Mediterranean Sea.
      The Revolutionary Guards naval force has a large inventory of small fast attack craft, and specializes in asymmetric, hit-and-run tactics. It is more akin to a guerrilla force at sea. Both navies maintain large arsenals of coastal defense and anti-ship cruise missiles and mines.
            In 2007, the two navies underwent a major reorganization of their responsibilities, with the IRGCN assuming control over operations in the Persian Gulf and the IRIN mainly focusing its efforts outside the Gulf. Both fleets are organized on geographic lines, with district commands along Iran’s southern and northern littorals.
            The first naval district for both commands is co-located in Bandar Abbas, near the Strait of Hormuz, suggesting that both services have overlapping responsibilities in this strategically significant area. Recently, the Revolutionary Guards Navy set up an additional district command in Bandar Lengeh that is responsible for defending Iran’s numerous islands in the Gulf.
How do Iranian naval capabilities compare to U.S. naval capabilities?
            Iran’s military leaders recognize that the United States is a technologically superior adversary and that Iranian naval forces would suffer major losses in any conventional conflict. For this reason, they have developed an asymmetric strategy that plays to Iran’s strengths while taking advantage of their adversaries’ weaknesses, including the U.S. aversion to casualties.
            Geography plays a central role in this regard. The confined operating space in the Gulf and especially the narrow Strait of Hormuz complicates U.S. operations and mitigates some of the U.S. Navy’s technological advantages. In a conflict, Iran’s naval forces would seek to overwhelm their adversaries’ defenses with mines, coastal defense cruise missiles, and swarms of small boats. Submarines and frigates would form the outer ring of Iran’s layered defense strategy.
            While the U.S. Navy would almost certainly prevail in an extended conflict, Iran’s naval forces would likely seek to inflict enough casualties to raise the cost of victory to an unpalatable level.
Iran held a wide-ranging naval exercise in December 2012. What new capabilities did Iran demonstrate — and what was its message to its neighbors and the United States? 
            Velayat 91, a combined Iranian Navy and Air Force exercise, featured test launches of a variety of missile systems as well as naval and amphibious maneuvers. The extensive testing of anti-ship cruise missiles was particularly noteworthy. So were the testing of the new Ra’d air defense missile — an “optimized” version of the Russian S-200 — and several subsurface warfare drills. Iranian maneuvers also featured the IRIN’s new, domestically produced Tondar hovercraft.
            According to official statements, the exercise was intended to “send a message of friendship to neighboring countries.” But its primary purpose was undoubtedly to deter the United States and its allies from attacking Iran. Many of the weapons systems and platforms featured in the exercise play an important role in Iran’s anti-access, area denial strategy.

Read Gulf I: Iran's Power in the Air

Read Gulf II: Timeline of U.S-Iran Encounters
Michael Connell is director of Iranian Studies at the Center for Naval Analyses, a non-profit institution that conducts research and analysis in Washington D.C.
Photo Credit: Suspected small craft of the IRGCN 080106-N-0000X-005.jpg by Navy.mil on Jan. 6, 2008
Department of Defense photo of Kilo-class submarine via Wikimedia Commons
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