An unprecedented joint appearance by two men frequently described as the respective "fathers" of the Soviet and American hydrogen bombs featured sharp disagreement on whether space-based defenses would bring world harmony or nuclear war.

Andrei Sakharov, the Soviet scientist who has become his nation's foremost human rights activist, said deploying such a defense system would "destabilize the world" and could trigger nuclear war between the superpowers.Edward Teller, one of the principal American advocates of deploying the "Star Wars" defense system, said it could lead to a "world neighborhood" of cooperation and peace.

The two scientists aired their views Wednesday evening at a banquet honoring Teller as a pioneer in the field of nuclear physics and for his advocacy of the Strategic Defense Initiative, SDI. It was sponsored by the Ethics and Public Policy Center, a conservative research group.

Sakharov, 67, winner of the Nobel and Albert Einstein peace prizes, attended the dinner as part of his first trip outside his native land.

In a speech at the beginning of the banquet, Sakharov praised Teller as a man of principle and conviction but said deploying the Strategic Defense Initiative, as the "Star Wars" plan is formally known, would be "a great error."