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Serb military targets were picked far in advance. The Clinton administration, after months of diplomatic dead ends, determined it was time to take a stand against Slobodan Milosevic. NATO's credibility was on the line.

That was Bosnia in 1995, and it was Kosovo in 1999.

But beyond surface similarities between efforts to end the Bosnian War and the Kosovo conflict, there are deep differences. The most important: Kosovo was the first time the defensive NATO alliance had taken the offensive in its 50-year history, attacking a sovereign nation to try to end a civil war.

Six days into the airstrikes, Milosevic was as defiant as ever as NATO commanders expanded target lists to include roving Serb Army and police troops accused of murdering ethnic Albanians now on the run by the thousands.

"We're relying on NATO and U.S. forces to essentially do something that could change boundaries on the European continent," said Simon Serfaty, director of European studies at the Center for Strategic and International Studies. "This is not a small decision."

In 1995, the Bosnian government asked NATO to help defend against Bosnian Serbs as the body count mounted to 200,000 after four years of massacres and civilian atrocities in the wake of the breakup of Yugoslavia. After an Aug. 28 Serb bombing of a Sarajevo market, allied bombers hit Bosnian Serbs in two separate campaigns of several days each.

This time, NATO airstrikes directly targeted Milosevic's forces.

In 1995, NATO sought to halt the battle against Croat and Muslim forces in regions that had already broken from Yugoslavia, a conflict Milosevic is accused of engineering in his quest for a "greater Serbia."

In the wake of the bombing, Milosevic quickly agreed to negotiate, leading to Dayton, Ohio, peace talks that succeeded in November. With Kosovo, he refused to budge.

By March 24, 1999, NATO missiles and bombs were pounding the Serbs in an attempt to force Milosevic back to peace negotiations with ethnic Albanians, who unilaterally signed a peace plan earlier in March.

Milosevic rejected the proposal, which would have given Kosovars autonomy and put 28,000 NATO peacekeepers in Kosovo to enforce the deal for at least three years, including up to 4,000 Americans.

There doesn't appear to be a clear end game to the conflict. Unlike in Bosnia, the warring parties in Kosovo showed few signs ahead of peace talks that they were exhausted by a year of bloodshed, refugee chaos and some 2,000 deaths. The most radical ethnic Kosovars still envision Kosovo as part of a "greater Albania" and are continuing to fight.

"The (1995) airstrikes were part of a larger political strategy for trying to end the Bosnian War," said Ivo Daalder, a former National Security Council official now at the Brookings Institution. "The airstrikes this time are almost the result of a failure of our policy. We still hope Milosevic will sign the peace agreement, but it would be very different (than Bosnia). It would be shoved down the throat of Milosevic by missiles."

Unintended consequences were among the largest Clinton administration worries about NATO airstrikes. The White House was also concerned that the conflict also could spread to Albania, Macedonia and beyond — the opposite of intentions.

"We're ... the KLA's air force," said Daalder. "We'll be changing the military balance on the ground, which could lead to quasi-independence or independence for Kosovo."

The Clinton administration doesn't support a secessionist Kosovo, but Daalder and other analysts said it may be inevitable. Ethnic Albanians make up 90 percent of the population in Kosovo, the historic heart of Serbian power.

Last year's action in Kosovo came a month before a 50th anniversary NATO summit in Washington, where leaders hoped to fashion a post-Cold War role for the alliance, formed to prevent the further spread of communism across Europe by the former Soviet Union.

"NATO's credibility is at stake," said Balkans Action Council's Kurt Bassuener ahead of the summit. The Council has long favored removal of the authoritarian Milosevic.