Could Iran shut the Strait of Hormuz, or significantly hinder traffic passing through it? A recent decision by the European Union to impose a total embargo on the purchase of Iranian oil has prompted threats from Tehran to close the world's most important oil chokepoint. However, an assessment of military capabilities deployed in the area, and of probable tactics, suggests that Iran would find it difficult or unpalatable to cause major disruption.
According to the United States Energy Information Administration, 17 million barrels of oil passed through the strait every day in 2011, or about 35% of all seaborne traded oil. Iran itself is heavily dependent on oil flowing through the strait: approximately 70% of the government's revenues come from oil exports, all of which currently transit the strait. Iran has no pipelines to its Indian Ocean ports or to countries to its east.
In late 2011 and early 2012, the Islamic Republic of Iran Navy and Iranian Revolutionary Guard Corps (IRGC) Navy conducted Velayat-90, a series of exercises that focused on sea denial. Although Iran possesses capabilities that could, at least temporarily, disrupt shipping, it seems unlikely that it would be able to close the strait for a prolonged period.
Iran's capabilities
Given the small size of its surface fleet, with just six corvettes of meagre capability, there is no possibility that Iran could, in the traditional manner, assert command of the sea in and around the strait. Therefore, rather than attempting to mount a blockade, Iran is likely to pursue a denial strategy to attack isolated or poorly defended ships.
Key weapons in such an approach would be mines, torpedoes, rockets and anti-ship missiles. To avoid direct conflict with American or other naval vessels in the region, Iranian forces would probably use submarines and fast attack craft to deliver weapons at sea, or flat-bed trucks to launch anti-ship missiles from land. Air-launched weapons could also be used, particularly as part of a combined arms operation, to provide a greater chance of success.
The sophisticated air defence capabilities of US and allied Arab forces in the region could deter Iran from regularly using its aircraft to launch strikes in the Gulf. Iran's air force does, however, have the capacity to mount strike operations using the Russian Sukhoi Su-24 Fencer, as well as the ageing F-4 Phantom. Work has been undertaken to integrate anti-ship missiles on the F-4, and it is conceivable that a similar effort has been made with the Fencer.
Such tactics would resemble the latter years of the 'Tanker War'. Lasting throughout the Iran-Iraq War of 1980-88, but with a significant escalation in 1984, this primarily involved the targeting of vessels carrying Iranian or Iraqi/Iraq-allied Arab oil and offshore platforms. According to a comprehensive CSIS study, 259 tankers and carriers were attacked between 1984 and 1988. Iraq's attacks consisted primarily of French-supplied Exocet missiles launched from fighter aircraft, particularly Mirage F-1s and Super Etendards, while Iran deployed a mix of helicopter-launched ordnance, anti-ship missiles (particularly the Chinese-manufactured Silkworm) and rockets, and a small number of mines.
The missile threat
Given the experience of the Tanker War and what is known about Iran's current capabilities, anti-ship missiles would be a significant consideration for US and allied forces. Iran's anti-ship missile inventory consists almost entirely of Chinese weapons. Supplies began in the mid-1980s and continued in spite of pressure from Washington on Beijing. Iran is thought to have initially received HY-1 (CSSC-2 Silkworm) and HY-2 (CSSC-3 Seersucker) anti-ship missiles. During the Tanker War it deployed coastal-defence variants of the CSSC-2/CSSC-3 in the Strait of Hormuz. In the 1990s, Iran acquired the C-801(CSS-N-4 Sardine) and the longer-range C-802 (CSSC-8 Saccade). These have been deployed on ships, and have also been vehicle-mounted for coastal defence. The C-802 is often referred to as Noor, though Tehran often reuses names for different systems.
