President Clinton, in a news conference aboard Air Force One flying back to Washington Sunday, said the United States would consider sending troops to police a neutralized Golan Heights, in consultation with Congress and if both Syria and Israel agreed.

"As for U.S. troops," Clinton said, "obviously if both sides made an agreement and both sides wanted us . . . we would have to give it serious consideration." Clinton said the subject would be one that "we would have to talk to the Congress about."Clinton, wearing jeans and sipping a soft drink, spoke to reporters as Air Force One was still about four hours away from Washington and several hours after he concluded his talks with Syrian President Hafez Assad in Geneva.

Clinton described Assad as "tough, very tough" and said, "I think he has reached the conclusion that in the interest of his people, his administration and his legacy can make a meaningful and lasting peace." Clinton added, for emphasis, "I believe that."

Clinton added, "Today is the first time he had ever explicitly said he wanted an end to hostility with Israel . . . that peace with him meant normal peaceful relations."

In considering the future of the Golan Heights, Assad stressed that "Israel's security was not all that was at stake" and that, "Damascus was closer to the Golan than Tel Aviv or Jerusalem," Clinton said. "Both sides need security assurances."

Clinton said he spoke to Assad at some length about U.S. objections to any Syrian support of terrorists and also expressed his desire that Lebanon be "an independent state."

Assad denied again, Clinton said, that his country had any part to play in the downing of Pan Am flight 103 over Lockerbie, Scotland, pointing out that the only son of a Syrian woman in his home territory was also a victim.

"This is an issue I never consider closing," Clinton said Assad told him. "If you ever have any evidence that any Syrian was involved you just let me know, we will take appropriate action," Assad assured Clinton.

Clinton said that as soon as he boarded Air Force One he called Israeli Prime Minister Yitzhak Rabin and President Hosni Mubarak of Egypt to "tell them what had gone on with the meeting." Clinton said he tried to reach King Fahd of Saudi Arabia but could not.

The Israeli government withheld formal reaction until it could hear from two U.S. officials who were dispatched to Jerusalem to provide details about what Clinton and Assad had said to each other in private.

There was a problem with the public remarks, Foreign Minister Shimon Peres said Sunday. "The tone," he explained, "was too positive to be disappointing, but it was too general to be satisfactory."

Calls for a "comprehensive peace" from both Clinton and Assad also reinforced doubts in Israel that Syria will come to terms with Israel until other Arab states and the Palestinians do.

But some high-ranking Israeli officials, most of them on the political left, were more upbeat, arguing that Assad had indeed uttered the words they had been seeking to move peace negotiations forward. Now it was Israel's turn to respond, they said.