The International Criminal Tribunal for the former Yugoslavia (ICTY) was established by the United Nations Security Council on 25 May 1993 and sits at The Hague in the Netherlands.

It is charged with bringing to justice people responsible for serious violations of international war or other crimes against humanity.

It was the first body set up to deal with war crimes since the Nuremberg and Tokyo trials following the Second World War.

Louise Arbour: "The following are accused..."

Chief prosecutor Louise Arbour draws up charges against suspects who are then tried before 14 judges drawn from around the world.

So far, 84 suspects have been indicted and two found guilty of war crimes.

Six of the accused have since died while charges against another 18 were dropped. One man has been acquitted.

A further 25 suspects are in custody though critics say the trials timetable will slip because of the tribunal's shortage of resources.

What evidence does it need to bring President Milosevic to trial?

Louise Arbour: "Indictment is not an end in itself"

The Tribunal requires two different types of evidence to successfully pursue a trial and has been gathering it for years.

Firstly, it needs evidence that war crimes have been committed in the former Yugoslavia. This is being supplied by a variety of sources but principally from witness testimony.

Secondly, it would have to show a chain of command from the perpetrators to the president, proving beyond reasonable doubt that he directed the action.

What does this mean for Milosevic - Can he sign a peace deal?

Balkans analyst Robert Fox: "This means no more Dayton for Milosevic"

The president, the first ever serving leader to be indicted, stands the risk of being arrested if he leaves Serbia. He theoretically risks arrest by travelling to Montenegro, the other remaining republic in the Yugoslav federation.

Any international assets he has - including alleged secret bank accounts in Cyprus - will be frozen to further curtail his chances of escape. The money will also be used as part of restitution in the event of the president being tried and found guilty.

The indictment means that President Milosevic would be unlikely to travel abroad to sign any eventual agreement - unlike in 1995 when he flew to Dayton, Ohio, to sign the Bosnia peace deal.

How would he be arrested?

Radovan Karadzic: Wanted

In practice the enforcement of the indictment depends on political decisions in the international community.

The tribunal relies on international forces such as Nato to arrest suspects.

In Bosnia, British and American troops in the S-FOR peacekeeping force have arrested some of the suspects and killed another in the attempt. But two key suspects, former former Bosnian Serb leader Radovan Karadzic, and General Ratko Mladic have not been arrested despite international protests.

Unless international troops enter Serbia there is little chance of the president being brought to trial - Nato would be unlikely to attempt a high-risk operation by elite forces such as the SAS to kidnap the president.

Why has this indictment come now?

Arrests: Tribunal needs Nato backing

While many Nato members have been cautious about how to prosecute the war, some, including Britain's prime minister Tony Blair, describe it as a "just and moral" act to defend innocents.

Louise Arbour is known for her fierce independence and her determination to see results at the tribunal - and has stressed that "indictments must not be an end in themselves".

While the indictment may muddy the diplomatic waters, prosecutors would see it as the logical moral endgame of a conflict fought for moral reasons.

But won't this seriously wound diplomatic efforts?

Kremlin: Moscow angered

While Nato leaders may publicly welcome the indictment, they may harbour serious private concerns.

Western leaders have threatened Balkan leaders with war crimes trials throughout the 1990s - but have been careful to avoid blaming President Milosevic directly, knowing that they have to deal with him at the conference table.

The indictment has already drawn stiff criticism from Moscow which has been working hard to broker a deal with Belgrade.