In 2000, Jeane J. Kirkpatrick made an acute observation that I've not heard any other observer point out: the switch from "liberal isolationism" to "global engagement" -- almost overnight -- that coincided with the arrival of the Clintons in the White House.
In Commentary, she wrote:
When the Reagan administration offered arms and training to the Nicaraguan resistance, law professors all over America pronounced the policy illegal and utterly rejected the argument that force could under certain circumstances be used to restore or protect democracies. As late as 1989, when the U.S. intervened in Panama under George Bush, leading liberals in and out of Congress described this action as the clearest possible violation of the UN Charter's prohibition on force, and professors of international law reminded all and sundry that the use of force against another state is never justified except in self-defense, a concept that was itself to be very narrowly interpreted.
These extremely negative attitudes also colored the liberal response to Saddam Hussein's invasion of Kuwait, even after the UN Security authorized force against him. And when, Security Council resolutions in hand, George Bush sought authorization from the U.S. Congress -- as required by the U.S. Constitution -- the outcome of the Senate vote remained in doubt to the very end, even though Iraq's invasion of Kuwait across an international border was as clear a case of aggression as could be imagined. The vocal opposition of leading Democrats to the U.S. role in the Gulf was finally silenced only by enthusiastic popular support for the performance of American armed forces and high-tech weapons.
But then came the great change. By the time they reentered government with Bill Clinton, a generation of 60s liberals had rethought their views on force and intervention. With the definitive end of the cold war and the arrival in power of a new foreign-policy team, liberal isolationism was -- almost overnight -- replaced by a new doctrine of global engagement. Hostility to the use of force gave way to doctrines of "peacekeeping," "democracy-building," and "nation-building." Over the past few years, force has been justified in the pursuit of diverse causes: separating parties to a conflict, disarming warlords in remote countries, "restoring democracy" (Haiti), "containing" conflict (Macedonia), providing "advisers" (Bosnia), and delivering Kosovo from ethnic cleansing.