Iran: The Threat to the Strait of Hormuz

The U.S. Fifth Fleet insisted June 30 that it would not allow Iran to "shut" the Strait of Hormuz following a thinly veiled threat June 28 by Maj. Gen. Mohammad Ali Jafari, commander of Iran's Revolutionary Guard Corps, to do just that. This back-and-forth rhetoric makes it worthwhile to examine Iran's military capability along this vital international waterway. The Strait of Hormuz is 21 miles across at its narrowest. The shipping traffic corridor itself is a mere 6 miles wide, with 2 miles each for incoming and outgoing traffic, separated by a 2-mile buffer. More than 90 percent of all oil exported from the Persian Gulf, or nearly 17 million barrels per day (bpd), transits this outgoing lane. This is nearly two-fifths of the world's oil supply. If the strait were closed, only about 3 million bpd of that could realistically be redirected through Saudi Arabia via a trans-Arabian pipeline. But there is no alternate route for the 18 percent of global liquefied natural gas volumes exported from Qatar and the United Arab Emirates. Effectively shutting Hormuz would thus have a very real impact on world energy markets, not to mention the already skittish equity markets. (click image to enlarge) Iran has multiple military options to exercise in any attempt to close down the strait. Tehran's military has been practicing just this since before the 1984-87 "Tanker War," and it has worked extensively in recent years to refine its capabilities. While closing the waterway would be a complex and intricate operation for both Iran and the United States, the following snapshot provides a summary of how it would play out. Iran can use anti-ship missiles to this end in numerous ways. It has coastal missile batteries arrayed along its Persian Gulf coastline, along the strait itself and on islands near the major shipping lanes. Equipped with missiles ranging from the obsolete Silkworm to the C-802 missile (one of which struck Israel's INS Hanit in 2006), they probably all would be effective in engaging undefended and unescorted supertankers. Iranian missile boats also are stationed up and down the coast. They could swarm into the Persian Gulf and the strait in an attempt to sink commercial vessels and even U.S. warships further offshore, and continue to operate from islands and coves along the coast. Meanwhile, Iran's three Russian-built Kilo-class submarines could put to sea and lurk quietly in the warm, acoustically challenging waters of the Persian Gulf. These subs could deploy naval mines and launch both anti-ship missiles and torpedoes. Mining is perhaps the single most likely tactic Iran would use. Tehran has amassed an arsenal of naval mines, and mining would be one of the most lasting and time-consuming tactics to counter. Iranian forces would use both surface and submarine assets — some more surreptitious, some less so — to attempt to saturate the Gulf. The architecture of any attack would be tailored by what Iran has observed and thinks it knows about U.S. situational awareness and standard operating procedures along its coast. If Tehran could effectively coordinate its forces, they might achieve some early successes in a surprise attack. But the U.S. Fifth Fleet carefully monitors Iranian naval activity, and any meaningful surge of Iranian forces to sea — especially by its Kilos — would be noted, putting U.S. forces on a heightened state of alert. (The U.S. Navy already is on its toes, especially given recent incidents in the strait.) The Pentagon has lived and breathed this particular threat since at least the outbreak of the Tanker War in 1984, and has war-gamed it extensively. The more ambitious and broad the Iranian effort to shut the strait, the less likely preparations and early maneuvers would go unnoticed by the Fifth Fleet. Nevertheless, as soon as the first hits were detected and an attack recognized, further tanker traffic in the strait would be halted. U.S. fighters would be scrambled, establishing air superiority almost by default. It would be all downhill from there for Iran. It would take time — maybe a day or two — to break out and tweak already written and regularly updated war plans and target sets. Some assets probably would be pulled from Iraq while reinforcements were organized stateside. It is a rare day when there is not a U.S. carrier strike group (CSG) at sea in the Persian Gulf or Arabian Sea. Much of the initial counterattack would likely come from the carrier air wing and the offensive punch of the CSG itself. Most coastal missile battery sites already have been pinpointed, and these would be among the first things destroyed in an impending U.S. counterattack. Many would be struck by Tomahawks, land-attack Harpoons and other standoff munitions. Any warships or subs left in port would be targeted at the pier, and the major ports would be monitored for ships returning to rearm and resupply. The Kilos would be relentlessly hunted down. As they are some of the most potentially dangerous Iranian assets in play, the U.S. Navy would be loath to miss an opportunity to eliminate them permanently. The mines would be more challenging and would take more time. The United States has several mine countermeasure ships homeported in Bahrain and as many as five in any theater at a given time — enough to quickly begin the work of assessing the extent of the Iranian mining operation and beginning to sweep the strait. These ships would be supplemented by other international and regional mine warfare assets. The U.S. counterattack would progressively weaken Iran's capability to deploy further mines. Lanes could slowly be swept and patrolled, although too many variables to address here would effect the timetable. Iran is under no illusions about the result of such an action — namely, that it would fare poorly. Any attempt to "shut" the Strait of Hormuz would be a direct challenge to one of the foremost U.S. Navy objectives: freedom of the seas. The price of such an action would be Iran's naval and sea denial capabilities in the Persian Gulf, along with the political leverage those limited capabilities currently offer. Geopolitically, with oil prices at all-time highs, no one in the region is interested in disrupting exports from the Gulf. There is simply too much money to be made. Tehran, already something of a pariah in the Arab world, would be further obliterating any chance of striking a deal over Iraq to consolidate Shiite influence to its west, something more fundamental to core Iranian geopolitical interest. In addition, "closing" the strait — especially with nondiscriminatory means like naval mines — would also entail blocking Iranian crude exports. Since this is Tehran's single largest source of hard currency and tax revenues, such an action is a particularly unattractive alternative. This is especially true because the Iranian government is already feeling the financial crunch of the increased cost of importing refined gasoline. Meanwhile, other "targets of opportunity" along the coast (read: the Bushehr reactor) would be unlikely to escape U.S. wrath. And in exchange for shooting itself in its own fiscal foot and further isolating itself from the Arab and international communities, Tehran would face devastating losses to an entire branch of its military — and risk giving the United States an internationally acceptable excuse to conduct an air campaign against it.