The United States has missed its opportunities to withdraw from Vietnam and now must stay and fight, Lee Kuan Yew, Prime Minister of the Republic of Singapore, said at Harvard yesterday afternoon.

"The bus stopped several times and you should have gotten off," Lee told an audience of 125 at the Dunster House Forum. He cited 1954, 1956, and 1961 as times when the United States could have refused to fight in Vietnam. The killing of Diem, Lee said, was America's last chance for withdrawal, in his view a "far better" policy at that time.

Eventually Leave

The Prime Minister said that he wants the Americans to leave Vietnam eventually. But now, he stressed, the United States must show strong military counterforce. Firm American resolve would probably make the North Vietnamese willing to negotiate, Lee said.

In urging continued American effort in Vietnam, Lee spoke of American long-range interest in a stable non-communist government.

He stressed that the United States must try to find a group of South Vietnamese who can assume leadership. He charged that in 1954 the British and Americans "systematically" eliminated any alternative leadership to Diem's.

Action taken in Singapore, said Lee, is an example of a better solution to a problem such as Vietnam. The Prime Minister explained that the British, finding that they could not resist both the Communists and the nationalists, allowed power to go to "the most competent of the non-Communist groups." He boasted that in a free ballot today the Communist would receive no more than 13 per cent of the vote.

Wants To Talk

Lee originally planned only to visit the Center for International Affairs while at Harvard. In talks with President Johnson on Wednesday, however, Lee expressed a desire to meet with American students.

His request was channeled to Alwin M. Pappenheimer '29, Master of Dunster House, who arranged for Lee to speak at the Forum. Amid laughter and applause, Lee explained, "I've come here to sample opinion" and "to find out what other contingency plans I must make."