Free Preview of Members-Only Content

The United States insisted June 30 that Iran would not be allowed to "close" the Strait of Hormuz, in response to Iranian warnings to the contrary.

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.

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.