U.S. and Middle Eastern analysts say Iran is rapidly gaining new capabilities to strike at U.S. warships in the Persian Gulf, amassing an arsenal of sophisticated anti-ship missiles while expanding its fleet of fast-attack boats and submarines, the Washington Post reported on Thursday.

The new systems are giving Iran’s commanders new confidence that they could quickly damage or destroy U.S. ships if hostilities erupt, the analysts say.

Iran’s advances have fueled concerns about U.S. vulnerabilities during the opening hours of a conflict in the Persian Gulf.

Increasingly accurate short-range missiles - combined with Iran’s use of “swarm” tactics involving hundreds of heavily armed patrol boats - could strain the defensive capabilities of even the most modern U.S. ships, current and former military analysts say.

In recent weeks, as nuclear talks with world powers have faltered and tensions have risen, Iran has repeated threats to shut down shipping in the oil-rich Persian Gulf region. Its leaders also have warned of massive retaliation for any attacks on its nuclear facilities.

Last week, Iran’s Foreign Ministry declared that the presence of U.S. warships in the Persian Gulf constituted a “real threat” to the region’s security.

Pentagon officials have responded by sending more ships, urged on by Congress as well as U.S. allies in the region. This month, the Navy announced that it would deploy the aircraft carrier USS John C. Stennis to the Middle East four months ahead of schedule. The shift will keep two carriers in the Persian Gulf region.

The United States also has announced new military exercises in the region, including a mine-sweeping drill in the Persian Gulf, and has moved to add new radar stations and land-based missile-defense batteries in Qatar.

Iran’s increased power to retaliate has led some military experts to question the wisdom of deploying aircraft carriers and other expensive warships to the Persian Gulf if a conflict appears imminent.

A 2009 study prepared for the Naval War College warns of Iran’s increasing ability to “execute a massive naval ambush” in the Strait of Hormuz, a narrow waterway dotted with small islands and inlets and perfectly suited for the kind of asymmetric warfare preferred by Iran’s commanders.

Since 2009, analysts say, Iran has added defensive and offensive capabilities. Some of them have been on display in recent months in a succession of military drills, including a missile exercise in early July dubbed Great Prophet 7.
In April Pentagon assessment noted that Iran’s arsenal now includes ballistic missiles with “seekers” that enable them to maneuver toward ships during flight.

Modern U.S. warships are equipped with multiple defense systems, such as the ship-based Aegis missile shield. But Iran has sought to neutralize the U.S. technological advantage by honing an ability to strike from multiple directions at once. The emerging strategy relies not only on mobile missile launchers but also on new mini-submarines, helicopters, and hundreds of heavily armed small boats known as fast-attack craft.

These highly maneuverable small boats, some barely as long as a subway car, have become a cornerstone of Iran’s strategy for defending the Persian Gulf against a much larger adversary. The vessels can rapidly deploy Iran’s estimated 2,000 anti-ship mines or mass in groups to strike large warships from multiple sides at once, like a cloud of wasps attacking much larger prey.

A Middle Eastern intelligence official who helps coordinate strategy for the Persian Gulf with U.S. counterparts said some Navy ships could find themselves in a “360-degree threat environment,” simultaneously in the cross hairs of adversaries on land, in the air, at sea, and even underwater.

“This is the scenario that is giving people nightmares,” said the official, who spoke on the condition of anonymity in discussing strategy for defending against a possible Iranian attack.

The Iranian naval buildup is described by U.S. officials as part of an effort by the Islamic Republic to bolster its military credibility in the region.

The Pentagon’s April assessment said Iran was making steady progress in developing ballistic missiles capable of striking targets in Israel and beyond.

“Iran has the capacity to attack, from Argentina to Venezuela, in Asia, in Europe and throughout the Middle East,” Danielle Pletka, a defense expert at the American Enterprise Institute, said Wednesday in testimony before the Senate Foreign Relations Committee. “It seems naive to believe it does not have the capacity to launch attacks in the United States.”