By Dan De Luce

WASHINGTON, Dec 29, 2011 (AFP) - Iran could make good on its threat and temporarily shut down or disrupt oil shipping through the strategic Strait of Hormuz, but it would trigger a devastating US military reaction and leave Tehran utterly isolated on the world stage, experts say.

While Iran is invoking a possible closure of the vital strait as it faces the prospect of punitive sanctions, analysts say Tehran may be more inclined to take smaller-scale action short of mining the channel.

With an estimated 2,000 mines in its arsenal, Iran could possibly plant several hundred in the strait before being detected.

Such a move would either shut down the strait or hamper shipping traffic in the narrow channel enough to cause havoc in the world oil market, analysts said.

But laying mines in the strait would represent a clear act of war and Iran would face a massive US military response while antagonizing governments around the world, said Anthony Cordesman of the Center for Strategic and International Studies.

In such a scenario, "everyone in the Gulf is going to support outside intervention," Cordesman told AFP.

Iran would be putting much of its military power and its economy at risk by plunging into a direct confrontation, he said. "This is a country that does not have a modern air force or modern navy."

US-led military action could include "attacks on nuclear facilities, or military production facilities or much broader attacks on Iranian air power," he said.

If the Iranians dropped mines into the Strait of Hormuz, the United States would face the painstaking task of removing the mines or at least clearing out a safe shipping lane while facing hostile fire from Iranian anti-ship missiles and swarms of small boats.

Sophisticated US warplanes likely would be able to take out much of the Iranian missile arsenal and air defenses, but the conflict could drag on depending on Iran's ability to hide its weaponry in an initial assault.

Some optimistic assessments predict the strait would only be closed for a matter of days but other experts take a more pessimistic view.

A 2008 study concluded that "the experience of past mine-warfare campaigns suggests that it could take many weeks, even months, to restore the full flow of commerce, and more time still for the oil markets to be convinced that stability had returned," wrote academic Caitlin Talmadge in International Security, a Harvard University journal.

With Iran relying on the strait as an economic lifeline for its own oil exports, analysts and officials say Tehran might instead opt for lower-level action that would cause a spike in oil prices.

"You have an extremely wide range of asymmetric options that don't have to be anywhere near the strait," Cordesman said.

Iran could choose to harass or board commercial ships in the Gulf and stage searches, said Alireza Nader, an Iranian specialist at the RAND Corporation think tank.

In 2007, Iran seized a crew of British sailors and marines, alleging their boats had crossed into Iranian waters.

The last time Iran confronted American warships in the Gulf, during the Iran-Iraq conflict in the 1980s, it was badly outgunned.

Since then, Iran has sought to bolster its naval power and coastal defenses, investing in more powerful mines, mobile anti-ship missiles, submarines and a large fleet of smaller boats.

A US military officer on Wednesday dismissed Iran's threats over the strait, saying the statements out of Tehran were "mainly rhetoric" and that it was unlikely the Islamic republic would be willing to take such a volatile step.

"Our priority is freedom of navigation. And we would do whatever is necessary to make sure the area is open," said the officer, who spoke on condition of anonymity.

But there would be limited objectives for any US operation it would be tailored "to things that they're doing" near the strait, he said.

Iran is threatening to choke off the Strait of Hormuz as part of a high-stakes game in which it hopes to discourage countries from backing tough sanctions over its nuclear program, said Nader.

There was a growing danger that a low-level provocation by Iran, such as the seizure of a ship belonging to a Gulf state, could trigger an escalating chain reaction -- even though neither Washington or Tehran wants a conflagration, he said.

"The issue is tensions are so high, even if Iran is bluffing, there's a lot of room for miscalculation by both sides," he said.

"Iran is using this as a deterrent but if it goes too far, it might have a war on its hands."

ddl/ao