For decades, the Soviet Union has been the chief supplier of weapons to Iraq, although it supported the United Nations' embargo and suspended all military sales to Iraq after Saddam invaded Kuwait. Now that the war is over and Saddam's armies crushed, will the Kremlin step in and help him rebuild?

Unfortunately, the eventual answer may be "yes."British Prime Minister John Major visited President Mikhail Gorbachev last week and tried to get a promise that the Soviets would not rearm Iraq. He was unable to come up with any guarantees.

Given the fact that Moscow was on the same side as the United States and the U.N., why would the Soviets once again pour weapons into Iraq, thus creating the potential for future trouble? There appear to be several reasons:

- Iraq is a former client state of the Soviets, and Gorbachev would like to maintain good relations despite supporting the U.N. vote. It was Moscow that Saddam turned to in a belated attempt to get a cease-fire when it became obvious his armies were being devastated.

Gorbachev wants a Soviet role in the Middle East. By helping Iraq and playing up the fact that it did not have troops in the battle, the Soviets can appeal to the anti-Western mood in the Middle East. At the same time, by emphasizing its role in supporting the U.N. action, the Kremlin also gets credit from anti-Saddam groups. In such a situation, the Soviets are influential in both camps at the same time.

- The Soviet Union badly needs foreign currency, and arms sales represent a significant source of income. Between 1982 and 1989, for example, Iraq purchased $42.8 billion worth of weapons, most of them Russian. After the Iraq debacle, the Kremlin may have a hard time selling arms elsewhere since the Soviet weapons clearly came off second best compared with the dazzling performance by American weapons and equipment.

- Everybody else is selling weapons. The Middle East is the world's biggest and richest bazaar for armaments. Gorbachev can point to the United States and a host of others already rushing to make new arms deals. Washington has announced plans to sell Egypt $1.6 billion in planes and bombs. Much of the U.S. weaponry in Saudi Arabia will be transferred to the Saudis.

Yet allowing the Middle East to continue to bristle with all the latest weapons is lunacy. The region has some of the most volatile politics on earth, encompassing feuds, murderous hatreds, easily aroused emotions, greed, blind ambition and envy.

The United States is not exactly the best model for how to behave. Controversial U.S. sales were made to Iraq during the Iran-Iraq war because of American dislike of the Iranian regime. But in the Middle East, today's friend can quickly become tomorrow's enemy, and vice versa.

Clearly, the world needs to come to an international agreement on arms deals that would leave the Middle East less capable of mischief. Arms sales may be temporarily profitable, but in the long run they often cost far more than they are worth.