BERLIN -- By lashing out against Serbian targets across Bosnia, the NATO alliance yesterday leaped across a line its members had been nudging timidly for more than two years in the former Yugoslavia.
"We've moved from peacekeeping to peacemaking," said Ken Petrie, analyst at the International Institute for Strategic Studies in London. "We've crossed that invisible line."
In crossing that line, the air and artillery bombardments have destroyed far more than missile sites and ammunition dumps. For the moment, they've also wiped out a host of entrenched and embarrassing patterns of behavior the world has come to expect in Bosnia.
"All of us here in Belgrade got so used to to the empty threats [of the U.N.] and the pinprick attacks [by NATO] that no one expected this," said Milos Vasic, the writer who follows Bosnia for Vreme, an independent news weekly in Serbia's capital. "Now it's all new rules. It's not the same old story anymore."
Suddenly, for example:
* The large but outgunned Muslim forces of the Bosnian government have, in effect, acquired a sophisticated, unstoppable air force (NATO) and a crack unit of heavy artillery (the U.N. Rapid Reaction Force).
* The North Atlantic Treaty Organization and the United Nations are no longer the humiliated whipping boys of the bullying Bosnia Serbs. The roles are reversed.
* Russian protests on behalf of the Serbs don't seem to matter anymore on the diplomatic front.
But in rewriting the war's rule book virtually overnight, NATO's actions have also raised dozens of new questions. The biggest and most obvious ones are, why did this happen now, and what comes next?
The official answer to the first question is that the attacks were a response to Monday's Bosnian Serb mortar attack that killed 38 people in an open-air market in Sarajevo.
But equally, or more bloody attacks before -- such as the killing of 68 in the Sarajevo market in February 1994 and the killing of 21 by Bosnian Serb shelling of Tuzla in March -- have never drawn nearly such a response.
Neither has any of the shelling and sniping that has killed more than 10,000, mostly civilians, in Sarajevo during the past 3 1/2 years.
The real answer is more complicated. The most significant reason for the timing, analysts say, is that as of last weekend, when the last British troops left the Bosnian Serb-surrounded enclave of Gorazde, the United Nations no longer had any soldiers stationed in Bosnian Serb-held territory (except for a unit of Russian troops, generally considered sympathetic to the Serbian cause).
That means that, finally, the Bosnian Serbs would no longer be able to easily seize hundreds of U.N. troops as hostages to stop further airstrikes, as has happened in the past.
NATO warplanes have also been operating under a different, less timid command since the U.N. Rapid Reaction Force moved into Bosnia a few months ago.
Since then, the commander of U.N. forces has been able to deal directly with the NATO commander without non-military U.N. officials participating in the decision making.
The balance of the war has also shifted against the Bosnian Serbs lately, especially after separatist Serbs in neighboring Croatia were routed earlier this month by a Croatian offensive.
That brought on a split in Bosnian Serb leadership, with self-declared Bosnian Serb President Radovan Karadzic struggling to oust military commander Gen. Ratko Mladic.
The result of all those factors, Mr. Petrie said, was that the three nations dictating NATO's Bosnia strategy -- the United States, France and Great Britain -- finally fortified their political will to act.
"In the past you always had one country saying, 'Let's go and zap them,' and the others would say, 'no, no.' " Mr. Petrie said. "So even when you had an airstrike, what you usually ended up with was a $10,000 missile fired by a $20 million plane to destroy a tank that was worth nothing."
As for what comes next, the first thing will likely be more air and artillery attacks. With most of the Bosnian Serb anti-aircraft defenses destroyed already, and with U.N. artillery near Sarajevo aggressively targeting any Bosnian Serb gun that dares to fire at them or into the city, further airstrikes will likely continue until most Bosnian Serb gun positions around the city are either silenced or moved out of range.
After that, the next move will mostly depend on the Bosnian Serbs. Under Dr. Karadzic's leadership, the Bosnian Serbs have tended to be defiant even when it wasn't in their own best interests.
His brand of Serbian nationalism is the sort that revels in glorious PTC lost causes -- all the way back to the Serbs' disastrous defeat 606 years ago by the Ottoman Turks on the plains of Kosovo.
But if the more pragmatic General Mladic were to oust Dr. Karadzic, Western officials believe he would see the military reality and quickly be ready to bargain. Then, the mostly-Muslim forces of the Bosnian government would become the volatile element in the mix.