A relaxed and confident McGeorge Bundy, special assistant to the President for National Security Affairs, yesterday confronted some of his faculty and student critics. He told an overflow audience in Lowell Lecture Hall that the number of American troops in South Vietnam may be increased by 50 per cent to meet a Vietcong offensive in a critical period of combat during the months ahead.

In publicly answering the questions of the Administration's critics for the first time since the United States began bombing North Vietnam in early February, Bundy defended President Johnson's policy in Southeast Asia as "restrained" and "necessary."

He claimed that only through limited but effective use of force can the pressures undermining the Vietnamese government be contained and "meaningful negotiations" take place.

He also affirmed the desire of the Johnson Administration for a constitutional democracy in Santo Domingo, stating that General Imbert, head of the military junta, would not be "satisfactory" to Washington as a permanent leader of the Dominican government.

The acid and sardonic Bundy, who in past months has belittled academic criticism of the government, was absent from the platform. Instead, a polite, restrained, and occasionally affable man fielded questions from a panel of critics that included: Benjamin I. Schwartz '38, professor of History and Government; Albert M. Craig, associate professor of Japanese History; Thomas Skidmore, assistant professor of History; David Butler, president of the Harvard Graduate Political Club; Alan Gilbert '65, an officer of the Harvard-Radcliffe chapter of the May Second Movement; and Michael D. Lerner '65, a member of the CRIMSON editorial board.

In the course of the two-hour meeting, chaired by Carl Kaysen, Lucius N. Littauer Professor of Political Economy, panelists and members of the audience devoted most of their energies to a discussion of America's role in Vietnam.

Warning against the misuse of "misleading mechanical metaphors" like the Domino Theory, Bundy nonetheless parried the jabs of his questioners. He sketched a tableau of U.S. interests in South East Asia that was for the most part similar to the picture created by numerous government press releases in the past months.

Bundy would make no prediction as to when the war would end: "it will be long and it will be difficult." But he did confirm reports that the role and tactics of U.S. troops had been shifting significantly this spring. He stated that the American effort is predicated on the continued resistance of the South Vietnamese. Bundy explained, however, that American soldiers would definitely assume greater combat duties.

Otherwise his statements were strictly in keeping with previous information on Southeast Asia: weapons flow from North to South is increasing: Hanoi exerts considerable influence over the Vietcong: negotiations will be held only with those actually controlling the aggressive policy.

Bundy justified American intervention in the Dominican Republic by nothing that in the last week of April there was "persuasive evidence of a breakdown of authority" which could have been exploited by Communists.

He said that it was necessary to take decisive action immediately and that it was unfortunately much easier to encourage a man like Imbert than to discourage him. He asserted that the long range policy objective of the Administration was no different than that of most of its critics--to establish a stable, reform democracy. The real basis of the difference of opinion, he said, was in understanding the particulars of the situation.