As a Nobel Peace laureate, I, like most people, agonize over the use of force. But when it comes to rescuing an innocent people from tyranny or genocide, I've never questioned the justification for resorting to force. That's why I supported Vietnam's 1978 invasion of Cambodia, which ended Pol Pot's regime, and Tanzania's invasion of Uganda in 1979, to oust Idi Amin. In both cases, those countries acted without U.N. or international approval—and in both cases they were right to do so.