KUWAIT, OCT. 21 -- The massive American military build-up in the Persian Gulf, conceived to protect the oil flow from Arab allies and the principle of free navigation, now seems regarded less as a reassuring escort patrol than a volatile military presence that may ignite an expansion of the seven-year war between Iran and Iraq.

Far from bringing calm to the gulf, the American force of more than 20,000 men has provided a new target for revolutionary Iran and pulled reluctant Arab states on American coattails toward the battleground.

Iranian threats, restated today in Tehran, vowing quick retaliation for Monday's U.S. naval artillery barrage against an Iranian oil platform suggest that Iran's leaders were not impressed by the "measured" signal Washington was trying to send.

Moreover, the two-track U.S. policy to promote a U.N. cease-fire campaign while trying to enforce freedom of navigation under limited rules of engagement continues to lose momentum on both tracks.

The recent escalation in tension is forcing moderate Arab states into more militant defensive postures, bringing them to the brink of the kind of open confrontation with Iran that they have tried so painstakingly to avoid.

And, in subtle ways, the gulf conflict also has begun to polarize East and West on the issue, worrying some Middle East analysts that mutual suspicions between the United States and Soviet Union over each other's intentions in the region could soon affect efforts to improve the East-West dialogue.

What seems most apparent is that American policy in the region is under far more stress today than six months ago when the Reagan administration attempted to outflank a Kuwaiti-Soviet agreement to move a small portion of Kuwaiti crude oil in and out of the gulf on three Soviet-flag tankers.

No sooner had U.S. officials decided to counter the Soviet challenge by taking 11 Kuwaiti oil tankers under U.S.-flag protection than the inherent violence of the region exploded with a mistaken Iraqi missile attack on the USS Stark.

The loss of 37 Stark crewmen on May 17 changed the U.S. stake in the Persian Gulf overnight. And by July, when the U.S. Navy prepared to escort its first convoy up the steaming aquamarine waterway, an American armada appeared over the horizon in numbers that had not been expected here and with intentions that were unclear on both Arab and Iranian shores.

The pace of the violence has been intense ever since. An Iranian mine punched a hole in the reflagged supertanker Bridgeton on the maiden U.S. escort convoy, and mines remain a daily threat despite the deployment of U.S. and other western mine sweepers here.

The mine threat spurred U.S. forces to attack the Iran Ajr, caught laying mines Sept. 23. Two weeks later, U.S. helicopter gunships, responding to what may have been warning shots from Iranian gunboats near Farsi Island, cut loose with Gatling guns and rockets on three of the boats.

The Arab states, who hoped American power would send Iranian aggressors retreating for their shores, have instead faced a more resentful and resolute enemy.

Riots by hundreds of Iranian pilgrims in the holy city of Mecca drew Saudi gunfire on July 31, and Iran sent its gunboats against oil tankers bound for Saudi and Kuwaiti ports. Early this month, Iran launched 60 gunboats toward a joint Saudi-Kuwaiti oil field on the Arab shore, forcing a full mobilization of U.S. and Arab military forces to turn back the assault force.

But Iran, in ever shifting tactics, fired two Silkworm missiles on successive mornings last week, punching gaping holes in U.S.-owned or U.S-flagged tankers in Kuwaiti territorial waters.

The American response against Iran's Rostam oil platform has left Middle Eastern and western leaders wondering where the conflict is headed.

Iran's Prime Minister Hossein Mousavi asserted that the United States, using the Syrian government as an intermediary, has reinforced its message that the confrontation between the two countries should be left buried in the rubble of the Rostam platform.

This message appeared to echo the words of Defense Secretary Caspar W. Weinberger that the Rostam attack should be considered a closed episode.

{A Reagan administration source in Washington said only that Syria had been asked to "convey our well-known views" on the gulf situation, The Associated Press reported.}

Iran's news agency quoted Mousavi as saying, "Our response to the message was {that} we will not let any blow go unanswered. Compromise is impossible and we will retaliate {for} the attack."

Saudi and Kuwaiti military leaders have been forced to look after their own defensive interests, increasingly with U.S. advice and assistance, while Arab leaders in the six-state Gulf Cooperation Council continue to debate whether to invoke their mutual defense pact against Iran.

A joint Saudi-Kuwaiti aerial strike force, complete with U.S. Cobra gunships and U.S. sea surveillance planes, was reported poised at Saudi Arabia's Dhahran air base for quick deployment against seaborne threats.

In a rare display of force, Kuwaiti warplanes dropped live bombs during target practice in the gulf this week and began redeploying their U.S.-made Hawk missiles to the northern islands that face the Faw Peninsula, from which the Iranian Silkworm missiles reportedly were fired.

This sheikdom is so sensitized to incoming missiles that a sonic boom at 8 this morning set off reports that Iran had lobbed another Silkworm, this time onto the Khafji oil platforms shared with Saudi Arabia.

The danger of this escalation, expressed by a number of Arab leaders, is that it is building in a vacuum of active diplomacy to end the war.

U.S. officials said they expect the United Nations to move quickly to the enforcement phase of July's U.N. cease-fire resolution, which would impose an international arms embargo on Iran. But the consensus for such a step remains elusive, and the efficacy of closing the international arms bazaar to Iran is an open question.

As the U.S. military raises its profile in the region, some Arab leaders seem to sense a cooling by the Soviet Union and China to an international peace enforcement exercise that is spearheaded by the U.S. military.