MANAMA, BAHRAIN, AUG. 13 -- The speed with which the United States has been able to mount a massive buildup of air, naval and ground forces in the Persian Gulf is the result of a quiet, decades-long Western effort to develop an extensive military infrastructure on the Arabian peninsula.

What this has brought about, in the words of Middle East analyst Anthony H. Cordesman, is "a unique kind of strategic partnership that does not require treaties . . . or even open admission of its existence, if this is embarrassing to a gulf or Western state."

This week, as huge U.S. transport planes land at oversize airfields in Saudi Arabia, British fighter planes touch down in Oman and U.S. warships speed to shield Bahrain's ports, that strategic partnership is opening up for all to see. Military facilities built with U.S. expertise and Saudi petrodollars during the 1980s include the King Khalid Military City near the Saudi border with Iraq, an underground air-command center at Dhahran on the gulf coast, naval facilities along the Red Sea coast and prepositioned munitions stores sufficient to sustain U.S. forces for several months of combat.

Expanded air, naval and radar facilities are also available to British and U.S. forces arriving in Oman, at the tip of the Arabian peninsula, while the ruling family of Bahrain, a small island nation off the Saudi gulf coast, is expected soon to allow U.S. warplanes to land at a base that was quietly enlarged over the past decade to handle combat aircraft and heavy transport planes.

A Bahraini official declined to comment today on whether U.S. planes would be allowed to use the airport, and Bahrain has so far made no public statement about the gulf crisis other than to vote last weekend in favor of an Arab summit resolution authorizing a multinational Arab force to defend Saudi Arabia against the threat of an Iraqi invasion.

Bahrain already has an agreement with the United States under which the command ship of the U.S. Persian Gulf task force may dock at the island for 180 days a year. But so sensitive is the issue of military ties with the United States that the southern half of the island was closed to unauthorized visitors after construction to expand an air base began there in the early 1980s.

The extent of past logistical cooperation between the United States, Britain, Saudi Arabia and the smaller gulf states -- Oman, Bahrain, Qatar and the United Arab Emirates -- is still not fully known. But in general, besides selling billions of dollars' worth of armaments in the region, the United States and some of its NATO allies have encouraged the oil-rich sheikdoms to anticipate emergency military support by constructing airfields, defensive redoubts, hardened munitions stockpiles and sophisticated port and communications facilities that are far more elaborate than needed for their own, relatively meager defense forces.

"There has been a tremendous development in the last few years of the relationship between the small gulf states and the United States," said one Asian diplomat here. "There has been more and more coordination on security."

Senior U.S. and British officers also have forged close personal ties with military leaders in Saudi Arabia, Oman, Bahrain and other gulf states. Bahrain's crown prince, who is chief of the island's defense forces, studied at the General Command College at Fort Leavenworth, Kan., while Oman's military leader, Sultan Qaboos, was educated at Sandhurst, Britain's military academy.

Official secrecy about the extent of the military development program in the region, along with Saudi Arabia's policy up to now of barring Western forces from its soil, made it easier for the Saudis and other gulf leaders to dodge charges from Arab neighbors that they were surrogates for Western interests. Deep opposition in the gulf states to the close ties between the United States and Israel also required that the extent of military coordination be played down on both sides, according to Western analysts.

But while the military buildup has gone a long way to reveal the extent of the clandestine cooperation between the gulf states and the Western allies, the current crisis will also test both the efficacy of that planning and the firmness of the ties between the West and the deeply conservative Arab sheikdoms.

Iraqi President Saddam Hussein, whose invasion and annexation of Kuwait touched off the crisis, has seized on the U.S.-gulf cooperation as new ammunition for his belligerent rhetoric, calling the gulf leaders corrupt and urging poorer Arab nations to rise up and expel the U.S. forces.

Some Arabs and diplomats in the region speculate that by forcing Arab states to choose sides openly on the issue of U.S. troop deployment in the region, the crisis could contribute to a long-term realignment of Arab interests on such questions as the Iraeli-Palestinian issue. The Palestine Liberation Organization has backed Iraq, angering some in the threatened gulf states, which have funded the PLO heavily in the past.

But continued nervousness throughout the region about the potential adverse consequences of inviting U.S. forces onto Arab territory after a history of quiet, less complicated relations suggests that there will be a strong push to return to the earlier arrangement once the Iraqi crisis has passed. Said one diplomat: "The Arab countries will sleep with the United States, but they will never get married."