Law Of The Sea
Iran says closing the waterway is justified because governments like the United States and Britain have imposed economic sanctions on Tehran over its nuclear program, which they believe is a front for weapons development and which Tehran insists is peaceful. Iran's saber-rattling in the strait is aimed at heading off increasing efforts to curb its oil exports, and it says maritime law supports such a move.
But James Kraska, a professor of international law at the U.S. Naval War College's Center for Naval Warfare Studies, says relevant law in this case is the UN's 1982 Convention on the Law of the Sea.
"Under that convention, transit through international straits is guaranteed for all countries, so there would not be a legal basis to close the [Hormuz] Strait," he said. "And transit through the strait includes transit in the air, on the surface, as well as under the water. There's no requirement to seek the coastal states' permission, and there's no lawful basis for the coastal states to impede the transit."
Neither Iran nor the United States are among the treaty's 150 signatories, but Kraska says the convention is "customary law" that has been recognized for centuries. The waters in the strait have dual status, he says. They are technically Iranian territory, but they are also an international strait, and that gives foreign ships "a higher right of transit."
Naval Power Rules
But let's say Iran blocks it anyway. Does it have the military capacity to then take on a naval power like the United States, which is certain to respond?
A 2008 report by the Washington Institute for Near East Policy said Iran was "essentially in control of the world's oil lifeline" and had the capability to "wage unique asymmetric warfare against larger naval forces." The institute's Michael Eisenstadt says blocking the strait is "something Iran has been preparing for for years."
"Iran has been investing for decades now on creating a naval guerrilla force which would have the capability of at least interfering with shipping through the Strait of Hormuz and perhaps closing it, at least temporarily, using a combination of mines, small boats, antiship cruise missiles, submarines -- both midget submarines as well as conventional submarines -- and most recently ballistic missiles," Eisenstadt says.
Karasik of the Institute for Near East & Gulf Military Analysis agrees. "Iran's specialty is asymmetric warfare," he notes. "This is what they practice in their simulations and their exercises. This includes the use of small ships or boats, also suicide boats, underwater warfare capability, combined with the use of ballistic and cruise missiles. So they can pack a punch if they are able to get these weapons off the ground."
Explainer: Iran's Threat to Blockade The Strait Of Hormuz