able to build powerful military machines on the basis of manpower, each putting between 400,000 and 1 million troops under arms, according to The International Institute for Strategic Studies in London. Saudi Arabia, struggling to build forces of little more than 70,000 men, in recent decades has tried to buy security by purchasing sophisticated weapons and maintaining close but quiet links with Washington.

Even the more modest Saudi forces have had to depend on foreign manpower -- a particular discomfort for Riyadh, given the Saudi Bedouins' cultural wariness of outsiders. Reluctant to take in such foreigners at all, Saudi Arabia years ago turned to Moslem Pakistan, under its former military leader, Mohammed Zia ul-Haq, to supply ground forces to supplement its own troops.

In 1983, Saudi Arabia agreed to arecent U.S.-Saudi relationship, Riyadh has sought Washington's aid when needed, but -- until yesterday -- has stopped short of inviting any U.S. offensive capacity on its soil. During the eight-year Iran-Iraq war, Saudi Arabia consistently tried to avoid direct conflict with a hostile Iran, breaking ties only after Iran backed an uprising in Mecca in 1987 and attacked its ships. During the war, the Saudis allowed the United States to fly AWACS surveillance planes from Riyadh, but insisted on running the operation jointly, partly in the form of training for the Saudi Air Force.

In 1987, when the war spilled into the Persian Gulf, threatening Kuwaiti exports (and, ultimately, oil production in Saudi and other offshore fields) the United States moved Marines, and naval and air forces in to