Leading Article: The time has come to show that Nato's threats aren't empty

AFTER A year of warnings from the British and the Americans, it looks as though Nato is finally going to use military force in Kosovo. The anti-war voices raised against the bombing of Baghdad will be horrified, questioning the purpose of air strikes and repeating the conventional wisdom that wars cannot be won from the air. Not that they will be wrong to do so. This is a solemn moment, and it is right that, before the lives of Nato forces are risked, we should hesitate.

It is alarming that the withdrawal of the Western observers from Kosovo has left the Albanian-speaking majority in the Serbian province at the mercy of the Serbian tanks. It is likely that air strikes on Serbian military targets would kill civilians. And it is certain that, if the West wanted to keep Serbian troops out of Kosovo, which is the only guarantee of the security and freedom of the Kosovar people, it cannot be done from the air. If Slobodan Milosevic, the Serb leader, were to choose to defy the West in Kosovo, the only way to stop him would be to wage a long land war against one of the most aggressive and highly motivated armies in Europe, which is a prospect few in the West have even begun to contemplate.

But what is the alternative? It is obvious that we should not have started from here. It was obvious that the lesson of Bosnia should have been learnt long ago: that the only way to face down the bullies of Belgrade is by the threat of force - and that the threat must be genuine. If Milosevic had been forced to this point a year ago, a series of massacres of Albanian- speaking Kosovars would not have happened, and the Kosovo Liberation Army would not have gained its hold or carried out so many reprisals (and the Serb minority in Kosovo has rights, too).

There are those who would argue that the use of force is better never than late. But they are the people who would have left the Kosovars to their fate, which would have been "ethnic cleansing" and migration. Their argument is similar to those who say that the sanction Saddam Hussein should face for trying to acquire weapons of mass destruction is a telling- off.

In the end, the use of force is justified and necessary. Robin Cook and Tony Blair have since last March told Milosevic that if he does not end the repression in Kosovo, he will face the consequences.

Each time, the Serbs did enough to buy a bit more time, but then wrote their insincerity in the blood of Kosovar farmers. Last July, Mr Cook became annoyed with his Shadow, Michael Howard, for suggesting that Nato's warnings were "empty threats". Now, at last, the time has come to show that they are not empty. It is a grim duty but, as in Iraq, it must be done.