VERY few people in Yugoslavia thought the cease-fire there (the sixth) would hold, and it hasn't. The Yugoslav Army is stepping up attacks and throwing more armor at the Croats both in the north and the south, near Dubrovnik.The fight in this senseless and dirty war appears to be evening out. The once-mighty Serbian-led Yugoslav Army is in disarray; morale is low. The scrappy Croats are capturing weapons stockpiles and learning how to fight. But parity may simply fuel the pride and ethnic hatred that characterize the war. The war has become personal. Will it last a year? Ten? The pain and economic chaos could last generations. Lord Carrington will reconvene the Hague peace talks today, but he is unlikely to find an agreement. The Army, grimly joked about as the "seventh Yugoslav republic," has to crack further than it has for the fighting to end. Talk within the European Community about a peacekeeping force in Croatia has lessened. This must be due to the "reality" factor of the war. Foreign troops would be stationed village by village across Croatia. Croats and Serbs would resent their presence; both would probably fire on them. Will parents in Denmark want their boys killed in a faraway conflict that neither side yet wants resolved? US Secretary of State James Baker last week articulated a new US policy on the war. He pointed for the first time to the Serbian government and the Serbian-led Yugoslav Army as responsible for the conflict. That puts the blame where it mostly belongs. Serb President Slobodan Milosevic asked for this war, and Croat President Franjo Tudjman foolishly gave it to him. Yet the US must make it clear that it is the leadership of Serbia, not its people, at fault. The US must avoid the bigoted "good Croat-bad Serb" mentality developing in Europe. The Croats are a more sympathetic player in the crisis. They know this and play the role well: We're European, Serbs are not, they say. Croats are good democrats, Serbs are not. Neither assertion captures the truth. For the US to play a constructive role in the crisis it must not allow Mr. Milosevic to play the "foreign card convincing Serbs the world is lined up against them. Already they feel misunderstood and defensive - partly because Milosevic's propaganda has been effective (though many Serbs don't believe it). Somehow the US and EC must cut through the Croat-Serb polarization. The "bad Serb" image plays well in Europe and helps Milosevic by traumatizing Serbs. The US must "de-personalize" the conflict and support moderate and federalist Serbs. That will help the Balkans, and Europe.