Presidential hopeful Wesley Clark is in The Hague testifying at the war crimes trial of former Yugoslav President Slobodan Milosevic. In two days of closed testimony, General Clark is expected to be questioned about the period when he was commander of NATO forces, during the alliance's 1999 bombing campaign against Yugoslavia.

The former Yugoslav leader has always insisted if any war crimes were committed in Yugoslavia, they were committed by NATO forces. Now he will get to question the man who led the military campaign against his country.

The last time Mr. Milosevic and General Wesley Clark were face to face was in January 1999, two months before NATO bombed targets in Kosovo and Serbia in an effort to get President Milosevic's government to stop its crackdown on ethnic Albanians.

The general can not talk about his testimony until it is finished Tuesday, but he told reporters outside the court that the former president's trial is evidence that the world cares about the victims of dictators.

"For the people of the region it is a very important experience. It is the rule of law," he said. "It is closure with the man who caused the deaths, or is alleged to have caused the deaths, of hundreds of thousands and the homelessness and refugee burden throughout Europe, some two million people driven out of their homes, and so forth. A decade of war in Europe. It is a very important precedent for what may be happening later with another dictator from another part of the world."

The public will not get to hear the exchange between General Clark and Mr. Milosevic until the end of the week. The tribunal has agreed to a Bush administration request for time to listen to the retired general's testimony and propose edits of any information that could threaten U.S. national security. It is an unusual move for the Tribunal, but judges will have the final say on any U.S. requests for deletions from Mr. Clark's testimony.

Many other witnesses have testified in closed session, usually to protect their identity, but only France is known to have demanded that its top officers give evidence behind closed doors.

Two state department lawyers will accompany General Clark during his testimony, which is also expected to shed light on the time the General spent with then-President Milosevic as a U.S. negotiator trying to end the war in Bosnia in the mid-1990s.

General Clark says he spoke to Mr. Milosevic for more than 100 hours over the course of four years. He has called the former president's trial "historic".

Slobodan Milosevic has been in court since February 2002, defending himself against 66 counts of war crimes and crimes against humanity allegedly committed during the wars in Bosnia, Croatia, and Kosovo.

General Clark is one of several candidates competing for the Democratic Party's presidential nomination, to run against President Bush next year.