United States Navy officers call it the ``Silkworm envelope,'' what is probably the most dangerous stretch of water in the tense Gulf. The area encompasses the Strait of Hormuz at the Gulf's entrance. Ships within this narrow passage are in range of Iranian Silkworm antiship missiles positioned on the Strait's northern shore.
US Navy ships sailing through the envelope on escort duty have always been specially wary, and use of Silkworms against US ships would be seen as a serious provocation.
Thus, officials reacted warily to reports that five Silkworms had been fired against a group of three US warships.
According to a report from reporters onboard, the frigate USS Jack Williams took violent evasive maneuvers and fired radar-confusing chaff as five missiles identified by officers on the ships as Silkworms approached. All missed, though one came close enough to cause some of the crew to dive for cover as it roared past the stern of the Williams.
Army Maj. Barry Willey, a US Central Command officer escorting the media pool, said the view from the Williams was ``both spectacular and frightening - contrails from missiles could be seen in almost every direction.''
Back in the US, officials said they weren't sure of the number or type of weapons fired at the Williams and accompanying ships. Activity on Monday was so intense that such details are still not clear, said Marine Maj. Charles Boyd, a spokesman at Central Command headquarters in Florida.
Though Gulf fighting appeared to have died down by mid-week, sporadic attacks by Iran continued. Two neutral tankers were hit by fire from Iranian patrol boats and set ablaze. The US was still searching Gulf waters yesterday afternoon for the crew of a US attack helicopter that was missing.
According to White House spokesman Marlin Fitzwater, Adm. William Crowe, chairman of the Joint Chiefs of Staff, told President Reagan yesterday that he had no evidence of a Silkworm attack. But Pentagon spokesman Dan Howard would say only that the US lacked ``positive evidence'' that Silkworms were used, adding that ``those ships in that particular group were operating well within the envelope of the Silkworms.''
``Any ship operating in such a circumstance that gets a track on the scope has to assume a worst-case scenario,'' Mr. Howard said.
It is possible that the warning system of the USS Williams misidentified incoming missiles. But if it is determined that Iran did unleash its Silkworm batteries, some US Navy officers believe the US policy of retaliation for provocative acts might necessitate a strike against Iran's missile launch sites.
Hitting oil platforms has long been seen by US officers as the most restrained military option open to them. Taking out Silkworm sites is seen as a second, more serious step.
If US leaders decide more severe military steps are necessary, military complexes on the Iranian mainland, such as Bandar Abbas and Bushehr, would be likely targets.