IRAN AND THE GULF. US weighs military options against Iran. But Pentagon plays down threat to US

US officials are preparing contingency plans for how the United States would retaliate if its warships were attacked by Iran in the Persian Gulf. A military strike is not the only option available. But US forces must be ready for action if needed, defense sources say.

``There are a host of targets. Selection depends on what you're interested in doing,'' says a US military analyst on the Mideast.

The administration is already close to a diplomatic move against the Tehran government. The State Department is reportedly urging new restrictions on US-Iranian trade. Iran last year bought $34 million worth of American goods, ranging from food to telecommunications gear.

If Iranian forces do in fact challenge the US presence in the Gulf, the White House has three levels of possible military retaliation to choose from, experts inside and outside the government say.

1.Revenge against the specific source of an attack. If Iran fired a Silkworm antiship missile at a US convoy, for example, Navy planes could bomb the Silkworm launch sites dug in near the Strait of Hormuz. If Revolutionary Guards mounted a speedboat attack, US warships might shell or rocket Iran's irregular Navy facilities on Farisiyah and Sirri Islands.

2.Strikes against general military targets in southwest Iran. Two large, modern port and airfield complexes would be easily within range of US forces: Bandar Abbas, near the strait, and Bushehr, across the Gulf from Kuwait.

The US might choose such targets if it can't determine where an attack came from. Bandar Abbas is the main base for the handful of destroyers and corvettes that remain in Iran's regular Navy. Bushehr is the air base that Iran's conservative Gulf neighbors perhaps fear the most, as it is close to their oil fields. An Iranian F-4 fighter could take off there and be over Saudi Arabia's most sensitive loading terminals in slightly more than 15 minutes.

Shiraz air base might also be in US range, as would the incomplete naval air facility of Chah Bahar near Pakistan, but the bulk of Iran's military is deployed at the front with Iraq or in the far north.

3.An attempt to restrict Iran's ability to fight its war with Iraq. At the top of the escalation ladder for the US might be destruction of Iranian oil loading facilities such as Kharg Island or even oil production fields, which would cripple Iran's economy and its ability to pay for weapons and troops. A naval blockade might have the same effect. ``It's the only thing you could do that would really hurt them,'' contends a congressional staff member who works on defense issues.

All of this is not to say that the US military now expects a showdown with the forces of the Ayatollah. Pentagon officials continue to play down the possibility of Iran's launching an overt attack, even in light of the recent Martyrdom naval exercises.

``The Iranians have really been quite circumspect,'' the military Middle East analyst says.

Many critics argue that getting sucked into a tit-for-tat war of retaliation with Iran would be a very unwise thing for the US to do. Ayatollah Khomeini has many options for escalating any such fight, terrorism among them.

In addition critics of the administration's Gulf policy say Khomeini would not be as affected by a US blow against his homeland as Muammar Qaddafi was. Unlike Colonel Qaddafi, Khomeini has a rock-solid grip on power; and the Iranian populace has accepted hundreds of thousands of deaths in the war against Iraq with few signs of discontent.

If Iran is in fact not intimidated by the sheer presence of US Navy warships and decides to go ahead and launch some sort of attack for which it is fairly clear who is responsible, administration officials will then face an ``ugly choice,'' says Joshua Epstein, a foreign policy researcher at the Brookings Institution.

Having committed the US in a highly visible manner to being the policeman of the Gulf, the White House would have to either interpret away the evidence and back down, or slap Iran back in kind.

Many analysts believe that if this scenario comes to pass, the administration will retaliate militarily. So much Navy force has now been concentrated in the Gulf area that people in the White House ``must be thinking about a Libya-type endgame,'' says a retired US official with extensive security policy experience.