The prospect of a U.S. or Israeli attack on Iranian nuclear facilities has conjured up a variety of dire scenarios: a stratospheric rise in oil prices, further radicalization across Middle East, and the resumption of mass bloodshed in Iraq, as Teheran unleashes its terrorist agents there. But all this talk of catastrophe still gives short shrift to one of the gravest potential threats:  Iranian attacks on shipping in the Persian Gulf.

Iran is bringing 21st century warfare to the seas by planning small-boat suicide attacks that would resemble in some ways the aerial and naval suicide missions launched by Imperial Japan during its last desperate days in the Second World War. At the Battle of Okinawa in 1945, the Japanese mixed unconventional and conventional tactics to kill 12,000 Americans and wound more than 33,000. Iran, by contrast, is threatening a purely unconventional naval war, including attacks on U.S. military targets and on international maritime traffic. Oil prices would spike, and Iran would enjoy a long-term profit, even if it temporarily could not export its own oil.

“Iran has developed a comprehensive doctrine of asymmetric warfare, based on its experience during the  Iran-Iraq War, as well as more recent conflicts,” writes Fariborz Haghshenass, a specialist on the Iranian military, in a superb monograph (“Iran’s Asymmetric Naval Warfare”) published recently by the Washington Institute for Near East Policy. Thanks to this doctrine, Iran holds the Persian Gulf and the Strait of Hormuz—the world’s energy lifeline—“in its grip.”

The Persian Gulf possesses 55 percent of the world’s crude oil reserves. Iran dominates the whole Gulf, from the Shatt al Arab on its Iraqi border to the Strait of Hormuz 615 miles away. Deployed from this immense seaboard are the Islamic Republic of Iran Navy and the Iranian Revolutionary Guard Corps Navy, or IRGCN. U.S. Navy officers told me they have had civil encounters at sea with the regular Iranian navy, but not with the IRGCN. The IRGCN is a fully mechanized terrorist force. Although it is the unconventional offshoot of the regular navy, it is actually slightly larger than its parent, with 20,000 reportedly heavily-ideological sailors. It promises an unprecedented fusion of a modern military with sea-based asymmetric force.

The IRGCN was established in 1985 and made its reputation during the Iran-Iraq War with a daring assault led by young Basiji frogmen on Iraq's Faw peninsula. But most IRGCN attacks on Iraq focused on Iraqi ships, and were vulnerable to early detection by the Iraqis. The IRGCN learned from the experience and embarked on a modernization program that included the purchase of anti-ship missiles on portable platforms, small fast-attack craft heavily armed with rockets and anti-ship missiles, and mines and mine-laying platforms.

The IRGCN also learned to exploit Iran's coastline, which is rugged with bays, inlets, coves, and islands well suited to conceal small bases. Iran has three major navy bases on the mainland, and three on the strategically valuable islands of Abu Musa, Larak, and Siri, smack in the middle of the Gulf near the Strait of Hormuz. The Iranian navies maintain 60 other small ports, and Revolutionary Guard personnel have embedded among local inhabitants in many other easy-to-conceal staging areas in fishing villages along the Iranian shore.

As Haghshenass observes in his monograph, Iran’s heavily armed smaller speedboats “can be launched discreetly...off the back of a flatbed truck under cover of darkness, during high tide without any special accommodations,” and with low risk of detection. The IRGCN will use its knowledge of coastal terrain to the utmost, perhaps as effectively as guerrillas in Afghanistan used their terrain against the Soviets and NATO.