The mine-hunting vessels will join eight similar craft already positioned in the region, including four other Avenger-class ships and four British Royal Navy minesweepers. The U.S. Navy also retrofitted a former amphibious transport dock, the USS Ponce, to serve as a dedicated mothership for other units in the Persian Gulf, and the Navy plans to send four minesweeping helicopters to the area.
The Navy also is moving to address what it has called a general deficiency in mine countermeasure capabilities. Its long-term plan largely rests on littoral combat ships — small, agile vessels that operate close to shore and are compatible with mine-hunting modules featuring helicopters and unmanned vehicles. However, development of the modules is significantly behind schedule, so the Navy has made efforts to upgrade its mine countermeasures craft in the meantime.
The current reinforcements and upgrades enhance only the Navy's ability to respond to and neutralize Iranian mines already placed in the Strait of Hormuz — not to prevent Iran from mining the strait in the first place. Despite upgraded U.S. capabilities, such an event would be disruptive. Consider that during the December 2011-January 2012 Iranian naval exercises in the Strait of Hormuz, Brent crude prices rose by 4 percent due to fears of increased U.S.-Iranian tensions, despite a lack of any open hostilities. Moreover, Tehran's ability to disrupt traffic in the strait is not just limited to naval mines; the Iranians also have a number of anti-ship cruise missile batteries and other, more asymmetric capabilities such as swarm boat attacks and naval commandos.
However, the main constraints Iran faces in the strait are not U.S. anti-mine capabilities. Instead, Tehran is wary of angering countries with which it has better relations. Such countries include China, which receives more than 40 percent of its crude oil via the Persian Gulf (whereas less than 25 percent of crude consumed by the United States transits through the strait). Disrupting traffic in the strait also would cut off Iran's own ability to export crude oil, on which it depends heavily for revenue.
Given these constraints, Iran understands that a disruption of traffic in the gulf is better threatened than actually employed. The Iranians then will likely resort to blocking the Strait of Hormuz only in a dire situation or while under attack. Still, the mere threat of a closure can deeply affect markets and raise the price of crude oil — a deterrent that the Iranians will continue to use to their advantage.