US RULED OUT ATTACK ON IRANIAN SILKWORMS U.S. military planners ruled out Iran's Silkworm missiles as a target in the retaliatory attack mounted on Monday for fear of being drawn more deeply into the Iran-Iraq war, defense and Middle East experts said. U.S. naval forces destroyed an offshore oil platform and raided another in what the administration called a "measured and appropriate response" to an Iranian Silkworm missile attack last Friday on a U.S.-flagged tanker in Kuwaiti waters. Private analysts generally agreed that going after the rig rather than an onshore economic or military target such as Silkworm launch sites reflected a careful bid by Washington to limit the political, military and diplomatic fallout both at home and in the Gulf. "It simply demonstrated the United States will take military action when they (Iran) take military action," Norman Polmar, a defense analyst and author, said. He said hitting the platforms had spared Iran the embarrassment of casualties on its own soil, possibly avoiding an escalating spiral of attack and counterattack. In addition, it minimized the risk to U.S. forces and the potential embarrassment of any losses, including aircraft that could have been shot down had they taken part in an attack. Anthony Cordesman, author of a new book on the Iran-Iraq war, said the United States apparently chose a limited target to keep alive the possibility that U.N. Secretary General Javier Perez de Cuellar might still persuade Iran to accept a Security Council call for a ceasefire. "We want the U.N. peace initiative to work if there's any chance at all," he said, adding that the action made it clear tougher steps would follow if Iran to attack Gulf shipping. In targeting an oil rig -- albeit one said by the Pentagon to have been turned into a military command post -- Washington also sent a message that it might be willing to attack Iran's economic lifeline. Pentagon officials said the platform had been used as a base for Iranian raids against shipping in the lower Gulf. "We have chosen a military target, but we also have shown Iran that we are willing to interfere with its oil-exporting capabilities," Cordesman said. He predicted the United States would respond to any future major Iranian challenges by hitting Iran's naval base at Bandar Abbas on the Straits of Hormuz, followed by mining the approaches to Iran's oil export terminal on Kharg Island. Defense Secretary Caspar Weinberger said on Monday the United States did not seek further confrontation with Iran, "but we will be prepared to meet any escalation of military action by Iran with stronger countermeasures."