Tension between Iran and the United States flared on December 28, 2011, when Habibollah Sayyari, commander of Iran’s navy, threatened to close the Strait of Hormuz, the 34-mile-wide passage through which more than one-third of the world’s oil tanker traffic travels. His televised statement that “closing the Strait of Hormuz is very easy for Iranian naval forces . . . easier than drinking a glass of water” came against the backdrop of naval war games, the third major Iranian naval demonstration in recent years. The Iranian military ended its exercise five days later with a barrage of missile tests signaling the peril facing warships and tankers alike.
War games may propel the Iranian Navy into the headlines, but the challenge the Islamic Republic poses to international shipping is broader and growing; indeed, it has been building for a quarter of a century. During the Iran-Iraq war (1980-88), Tehran and Baghdad each sought to target the other’s business partners. Between 1984 and 1988, in the so-called Tanker War, Iran’s navy and its parallel Islamic Revolutionary Guard Corps-Navy (IRGC-N) developed a doctrine of maritime guerrilla warfare using speedboats, mines, antiship cruise missiles, and, on occasion, aircraft to target neutral or enemy shipping.
Revolutionary leader Ayatollah Khomeini learned quickly, however, that it was one thing to target Kuwaiti or Saudi ships, and quite another to attack American vessels. Four days after the guided missile frigate USS Samuel B. Roberts struck an Iranian mine in international waters on April 14, 1988, President Ronald Reagan launched Operation Praying Mantis. After warning the crews of two Iranian oil platforms to evacuate, Reagan ordered the Navy to attack them. The Iranian Navy scrambled and confronted U.S. forces head on. For Tehran, it was a fateful mistake. By the end of the day, Iran had lost a frigate, a gunboat, and three speedboats, on top of the two oil platforms, in what had become the largest U.S. surface engagement since World War II.
The lopsided U.S. victory convinced Iranian leaders of the need to avoid sustained conflict at sea. Rather than seek bigger and better ships, Iranian strategists prioritized surprise and ambush. Their goal became not victory, but the ability to create enough casualties to make victory unpalatable for both the Pentagon and the American public. In short, they sought the maritime equivalent of the low-grade insurgency they subsequently perfected on land in Afghanistan and Iraq.
As the Islamic Republic pursues this asymmetric naval strategy, geography works to its advantage. The Persian Gulf is both narrow and shallow—its average depth is only 160 feet—so American warships and submarines have reduced maneuverability. Not only can Iranian speedboats idle in Iranian waters just minutes from international shipping lanes, but both IRGC-N small boats and unmarked smuggling dhows—the traditional wooden boats that ply the Persian Gulf—can shelter in rocky coves along Iran’s 1,000-mile coastline.
It is these Iranian speedboats, and perhaps Iranians undercover in civilian boats, that pose the gravest threat to U.S. ships, not the Iranian drones, which most recently made headlines when they claimed to have photographed the aircraft carrier USS John C. Stennis transiting the strait. In the last few months, the frequency and aggressiveness of Iranian speedboat probing of American ships has increased dramatically according to sailors in the Persian Gulf.
Iranian small boats’ growing aggressiveness is in line with the Islamic Republic’s new military doctrine. In September 2007, the new IRGC commander, Mohammad Ali Jafari, reorganized his land forces to focus inward. He argued, presciently as the June 2009 election protests demonstrated, that the Iranian people posed a greater threat to Iran’s theocracy than did external armies.
Because the army was required to keep the lid on at home, the Islamic Republic would have to rely far more on its navy to meet external challenges. During a visit to a Bandar Abbas naval base in July, Supreme Leader Khamenei blessed the Iranian Navy and its IRGC counterpart as “symbols of the might of the Iranian nation” and promised their expansion.
Three months later, IRGC-N commander Ali Fadavi elaborated upon Iranian thinking. “The military power of the United States is maritime,” he explained. “Naturally, the main battlefield is the sea, . . . and the Revolutionary Guards Navy will be the center of resisting and defending and safeguarding the Islamic Revolution.”