MOSCOW, AUG. 18 -- As Soviet President Mikhail Gorbachev mulls his next move in the rapidly escalating Persian Gulf crisis, he is faced by one embarrassing fact: Soviet-built planes capable of carrying deadly chemical weapons are sitting in Iraqi hangars.

An article published today in the authoritative Jane's Defense Weekly quotes U.S. intelligence sources saying that among the weapons the Soviets have sold to Iraq during their alliance of more than 30 years are 10 Su-24 bombers, known in the West as Fencers, which can drop chemical weapons on ground forces or on ships in the Persian Gulf and Mediterranean. Iraq, whose invasion of Kuwait on Aug. 2 has brought international condemnation and formation of a multinational force to oppose any further Iraqi conquest, has vowed to use weapons of "mass destruction and strategic deterrance" in the event of a U.S. attack on its forces massed along the Saudi Arabian border.

Gorbachev has sided with the West against Moscow's old ally and has indicated that the Soviet Union is willing to participate in a United Nations-directed military operation against Iraq. The extent of his break with Baghdad was indicated Friday when he acknowledged the reponsibility that accompanied the Kremlin's traditional support of a power that now threatens to use chemical weapons.

Explaining Moscow's realignment, Gorbachev said, "For us to have acted otherwise would have been unacceptable since the act of aggression was committed with the help of our weapons, which we agreed to sell to Iraq only to maintain its defense capability rather than to seize foreign territories and whole countries." Making his comments to military recruits and leaders in the Ukraine, he contended that Iraq was threatening the world with total war.

Though Soviet Foreign Minister Eduard Shevardnadze's bureaucracy is filled with officials considered sympathetic to Iraqi President Saddam Hussein and other radical Arab leaders, Shevardnadze has ensured that the Soviet foreign policy apparatus maintain a clear anti-Iraqi line. He has said that if the U.N. Security Council decides on a joint military action against Iraq in the gulf, Moscow will participate. Further indicating the Soviets' ties to Iraq's opponents, Shevardnadze has said he is in almost daily contact with Secretary of State James A. Baker III.

The decision to stand against Iraq can have mixed consequences for the Soviet Union. On one hand, an oil producer with the Soviet Union's production capabilities stands to reap great profits if world oil prices continue to climb. On the other hand, Moscow, with hundreds of Soviet citizens in Kuwait and about 8,000 in Iraq, has a direct human stake in not provoking Saddam.

Although Saddam on Thursday and Friday ordered American and British citizens in Kuwait and Iraq rounded up for possible use as living leverage against a Western attack, the Soviets there have have not yet been subject to such restrictions. Today, some of the first 224 Soviets to be evacuated from Kuwait said they had been told that all Soviet residents would eventually be released.

Some of the evacuees, who landed today at Moscow's Sheremetyevo Airport, said they had been treated decently by the Iraqis in Kuwait, and none reported being abused. Telman Alkatayev, leader of the trip and head of an oil-rig contruction team with which most of today's evacuees were associated, said Iraqi soldiers never "harmed or humiliated" the Soviets.

When the Iraqis invaded, the oil workers and their families were required to eat at a cafeteria in the small town near Kuwait City where they were living and working, and were given very little information about the escalating confrontation between Iraq and the rest of the world.

"We did not know there was a war going on," said Nona Akopyan, 10, who described her fright at the invasion. "I wanted to go off swimming, but my mother told me there was a war and I couldn't."

After a three-day, 1,200-mile bus trip from Kuwait to Baghdad to Amman, Jordan, along roads jammed with military vehicles, the Soviets boarded a chartered Aeroflot jet to Moscow this morning. About 120 more were expected to arrive later today, followed soon by a third group of 400, according to the news agency Tass.

Despite the treatment of Soviet citizens, the Foreign Ministry here responded with guarded concern to Iraq's decision to round up Western nationals.

"If these reports are true, this will probably become another reason for concern over the further development of events in the region," a Foreign Ministry statement said.

"We realize that the point in question is the safety of thousands of people and a possibility of such actions from both sides {that} will lead to another escalation of tension."