“If you ask me what keeps me awake at night, it’s the Strait of Hormuz and the business going on in the Arabian Gulf,” Adm. Jonathan W. Greenert, the chief of naval operations, said in Washington this week. 
 
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 Administration officials and Iran analysts said they continued to believe that Iran’s threats to close the strait, coming amid deep frictions over Iran’s nuclear program and possible sanctions, were bluster and an attempt to drive up the price of oil. Blocking the route for the vast majority of Iran’s petroleum exports — and for its food and consumer imports — would amount to economic suicide. 
 
 “They would basically be taking a vow of poverty with themselves,” said Dennis B. Ross, who until last month was one of President Obama’s most influential advisers on Iran. “I don’t think they’re in such a mood of self sacrifice.” 
 
 But Pentagon officials, who plan for every contingency, said that, however unlikely, Iran does have the military capability to close the strait. Although Iran’s naval forces are hardly a match for those of the United States, for two decades Iran has been investing in the weaponry of “asymmetric warfare” — mines, fleets of heavily armed speed boats and antiship cruise missiles hidden along Iran’s 1,000 miles of Persian Gulf coastline — which have become a threat to the world’s most powerful navy. 
 
 “The simple answer is yes, they can block it,” General Dempsey said on CBS on Sunday. 
 
 Estimates by naval analysts of how long it could take for American forces to reopen the strait range from a day to several months, but the consensus is that while Iran’s naval forces could inflict damage, they would ultimately be destroyed. 
 
 “Their surface fleet would be at the bottom of the ocean, but they could score a lucky hit,” said Michael Connell, the director of the Iranian studies program at the Center for Naval Analysis, a research organization for the Navy and Marine Corps. “An antiship cruise missile could disable a carrier.” 
 
 Iran has two navies: one, its traditional state navy of aging big ships dating from the era of the shah, and the other a politically favored Revolutionary Guards navy of fast-attack speedboats and guerrilla tactics. Senior American naval officers say that the Iranian state navy is for the most part professional and predictable, but that the Revolutionary Guards navy, which has responsibility for the operations in the Persian Gulf, is not. 
 
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 “You get cowboys who do their own thing,” Mr. Connell said. One officer with experience at the Navy’s Fifth Fleet headquarters in Bahrain said the Revolutionary Guards navy shows “a high probability for buffoonery.” 
 
 The Revolutionary Guards navy has been steadily building and buying faster missile boats and stockpiling what American experts say are at least 2,000 naval mines. Many are relatively primitive, about the size of an American garbage can, and easy to slip into the water. “Iran’s credible mining threat can be an effective deterrent to potential enemy forces,” an unclassified report by the Office of Naval Intelligence, the American Navy’s intelligence arm, concluded in 2009. “The Strait of Hormuz is a narrow chokepoint that could be mined effectively in a relatively short amount of time” — with disruptions within hours and more serious blockage in place over days. 
 
 Although the United States would respond with minesweepers, analysts said American naval forces might encounter layers of simultaneous attacks. The Iranians could launch antiship missiles from their coastline, islands or oil platforms and at the same time surround any American ship with missile-armed speedboats. “The immediate issue is to get the mines,” Mr. Connell said. “But they’re going to have to deal with the antiship cruise missiles and you’ll have small boats swarming and it’s all going to be happening at the same time.” 
 
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 The United States could take out the antiship missile launchers with strikes from fighter jets or missiles, but analysts said it could take time to do so because the launchers on shore are mobile and often camouflaged. 
 
 The tight squeeze of the strait, which is less than 35 miles wide at its narrowest point, offers little maneuvering room for warships. “It would be like a knife fight in a phone booth,” said a senior Navy officer. The strait’s shipping lanes are even narrower: both the inbound and outbound lanes are two miles wide, with only a two-mile-wide stretch separating them. 
 
 American officials indicated that the recent and delicate messages expressing concern about the Strait of Hormuz were conveyed through a channel other than the Swiss government, which the United States has often used as a neutral party to relay diplomatic messages to Tehran. 
 
 The United States and Iran have a history of conflicts in the strait — most recently in January 2008, when the Bush administration chastised Iran for a “provocative act” after five armed Iranian speedboats approached three American warships in international waters, then maneuvered aggressively as radio threats were issued that the American ships would be blown up. The confrontation ended without shots fired or injuries. 
 
 In 2002, a classified, $250 million Defense Department war game concluded that small, agile speedboats swarming a naval convoy could inflict devastating damage on more powerful warships. In that game, the Blue Team navy, representing the United States, lost 16 major warships — an aircraft carrier, cruisers and amphibious vessels — when they were sunk to the bottom of the Persian Gulf in an attack that included swarming tactics by enemy speedboats. 
 
 “The sheer numbers involved overloaded their ability, both mentally and electronically, to handle the attack,” Lt. Gen. Paul K. Van Riper, a retired Marine Corps officer who served in the war game as commander of a Red Team force representing an unnamed Persian Gulf military, said in 2008, when the results of the war game were assessed again in light of Iranian naval actions at the time. “The whole thing was over in 5, maybe 10 minutes.” ||||| Comments are filtered for language and registration is required. The Times makes no guarantee of comments' factual accuracy. Readers may report inappropriate comments by clicking the Report Abuse link next to a comment. Here are the full legal terms you agree to by using this comment form.
– Some of the US troops who left Iraq last month didn't move very far. As tensions with Iran rise, the US military has been quietly boosting its strength in the Persian Gulf, reports the Los Angeles Times. The move comes as US officials have warned Iran that closing the Strait of Hormuz, as it has threatened to do, would be a "red line" that would trigger an American response, reports the New York Times. New deployments have raised troop numbers in Kuwait to nearly 15,000 and there are now two aircraft carriers and their strike groups in the region. The Army's 1st Cavalry Division's 1st Brigade, which moved from Iraq to Kuwait, has been designated a "mobile response force" for the region. The buildup was requested late last year by Central Command chief James Mattis, the top US commander in the region. Pentagon officials say the deployments are not a preparation for war, but an effort to have a force ready to react quickly if a military crisis erupts in the standoff with Iran.