Military leaders yesterday were preparing contingency plans for possible retaliation against Iran for its Silkworm attack on a U.S.-flagged Kuwaiti ship, according to Pentagon officials.

Adm. William J. Crowe Jr., chairman of the Joint Chiefs of Staff, is "coordinating contingency options" in case the White House decides to take military action, officials said.

Military leaders reportedly were studying some options that have been in planning stages since the Navy began escorting reflagged Kuwaiti tankers through the Persian Gulf in July.

Officials note that Crowe has been cautious about engaging the military in such attacks in the past.

Pentagon officials reported no major movement of warships or military aircraft in the Persian Gulf as of late yesterday, however. The United States has placed one of its largest peacetime concentrations of power in recent years in the region. A battleship and an aircraft carrier group are stationed in the Gulf of Oman and North Arabian Sea area just outside the Persian Gulf, and 12 warships, two barges outfitted as armed bases for helicopter and other special operations and some supply ships are inside the gulf.

Army and Navy special operations antiterrorist teams have been involved in several major gulf incidents in recent weeks, capturing and sinking several Iranian ships.

Pentagon sources said the military would be more likely to strike Iranian military sites than economic targets.

U.S. intelligence sources have been surveying Iran for potential targets for months, according to Pentagon sources.

These could include coastal storage depots for mines, weapons and ammunition, Silkworm launch sites, and military installations, they said.

Iran has used mobile launchers for most of its Silkworm missiles, however, making strikes on those sites difficult, according to Pentagon officials. The weapon that hit the products carrier Sea Isle City yesterday was fired from a mobile launcher on the Iranian-occupied Faw Peninsula, sources said.

Iran's Silkworm sites, some permanent and some mobile, along the Strait of Hormuz, are potential targets as well.

In addition, some military officials have long eyed Iran's Farsi Island, base for the Iranian Revolutionary Guard's speedboat attacks against commercial shipping, and a terrorist training camp in southern Iran as potential targets.

Options for an attack include:An aerial night attack using the A6E Intruder, backbone of the Navy's aircraft attack force. The planes, based on the carrier USS Ranger, are equipped with sensitive infrared sensors to spot targets for "smart" laser-guided bombs. The plane, with a two-man crew, can operate in all types of weather.

Intruders could be refueled in the air after takeoff from the carrier, giving them a range of 1,500 miles, more than enough to hit an Iranian target far up the gulf and return to the ship. A cruise missile strike launched from the battleship USS Missouri or other combatants in the Gulf of Oman just outside the gulf. The land-attack version of the Tomahawk cruise missile with a conventional warhead has a range of about 550 miles and could reach many Iranian targets without requring the ship to enter the gulf. Pentagon planners had mapped out potential strike zones for such an attack before yesterday's Silkworm incident, according to sources.

In the past, some military officials have opposed using the Tomahawk because of concern the weapon could veer off course. The weapon's manufacturer, General Dynamics Corp., has argued that the 20-foot-long missile, which carries a 1,000-pound warhead, is extremely reliable. Specialized strikes using the Army's sophisticated Task Force 160, with its heavily armed helicopter gunships, or the Navy's SEAL (Sea-Air-Land) teams that could plant explosives around key targets. Both groups have been active in recent Persian Gulf operations. Task Force 160 attacked the mine-laying Iran Ajr Sept. 28 and the four Iranian gunboats last week.

Sources said the military would most likely use Intruder attack planes in any strike against a Silkworm site. And although many military officials would favor using the planes in other land attacks, officials said the Tomahawk cruise missiles could be effective against large land targets such as munitions depots.

In April 1986, bombers flying from carriers and Great Britain bombed military and government targets in Libya in a White House effort to "preempt and discourage" terrorism. The attack, which also used the Intruder attack craft, was rated by the military as an extremely successful raid.