Joschka Fischer was once a revolutionary and a pacifist. As a youth, he opposed the Vietnam War. But today, as German foreign minister, he argues passionately that for the first time since World War II, Germany has no choice but to use military force alongside its NATO allies to defeat Yugoslav President Slobodan Milosevic and his regime.

Fischer, who does not rule out the use of NATO ground forces in the Kosovo conflict, argues that fighting this war will help Germany overcome its reluctance to assert itself, a hesitancy that is a legacy of its Nazi past.

Interviewed at NATO headquarters in Brussels, Fischer, 50, said Germans of his generation learned two lessons from World War II. One was "never again war." The other was "never again Auschwitz." In Kosovo, he acknowledged, these two notions could not be reconciled. "It's a contradiction, but we have to live with it. If we accept Milosevic as a winner, it would be the end of the Europe I believe in," Fischer said.

"My generation asked our parents, `Why did it happen in Germany during the war and why didn't you resist?' " Fischer said. "This is the question we have to ask ourselves now." Both the German public and government were shocked, he said, that Milosevic was "ready to act like Stalin and Hitler did in the '40s: to fight a war against the existence of a whole people."

"The dream of Milosevic is a bloody nightmare," Fischer continued. "It's a dream that there should be ethnic purity in the Balkans -- all Serbians in one state and Albanians in another."

Fischer is the leader of Germany's environmentalist Greens party, junior partners in Social Democratic Chancellor Gerhard Schroeder's governing coalition. Backed by strong public support in Germany for military action against Yugoslavia, the Schroeder government has stood firmly behind NATO's 18-day-old air offensive.

Schroeder said Europe has a lot at stake in Kosovo, a predominantly ethnic Albanian province of Serbia, Yugoslavia's dominant republic. "It's not an issue of human rights -- it's a question of which Europe we will have in the 21st century," he said. "The moment we accept this criminal nationalism in the Balkans, we accept that Europe will not be the land of law and peace."

Four weeks ago, Fischer traveled to Belgrade and met with Milosevic for 2 1/2 hours. "I [warned] Milosevic that you will start a war with the U.S.," Fischer said. "I told him Germany did this twice in this century, and our experience was terrible." Milosevic, according to Fischer, replied that if the United States and its NATO allies attacked his country, they would face a situation worse than Vietnam.

"I told him, `This is not Vietnam, and you are not Ho Chi Minh,' " Fischer said.

Fischer also warned Milosevic that if he pursued his brutal crackdown against Kosovo's Albanians, Yugoslavia would be the loser. " `You will lose your idea of a Greater Serbia in a sea of blood and sorrow, and you will lose Kosovo if you continue this way,' " Fischer said he told the Yugoslav leader. " `Your Greater Serbia will be a rump Serbia.' "

The German foreign minister staunchly defended Secretary of State Madeleine K. Albright's handling of the Kosovo crisis. Dismissing American critics who say she was unprepared for the ferocity of Milosevic's actions in Kosovo, Fischer said, "Albright is doing a very difficult but good job. All of us underestimated the readiness of Milosevic to go to a full-scale war. All of us."

Fischer's hawkish position does not sit well with all his constituents. Many pacifists in the Greens party do not accept the idea of Germany fighting a war, he said.

Fischer noted that, given his early pacifism, he never would have expected to be granting an interview in NATO headquarters defending a bombing campaign. "But [we cannot] accept Milosevic's policies and bow our knees in front of this ethnic cleansing," he said. "We would give up all the successes of the last four decades in Europe."