A statement from the Bosnian Serbs said the Pale suburbs of Jahorinksi Potok and Ravna Planina were bombed, but gave no further details. There were no immediate reports of casualties. NATO said the Serbian account was wrong and that a single location had been hit.

The Serbian response to the air attack included entering three United Nations depots of confiscated weapons near Sarajevo and firing mortars at the city center, a United Nations spokesman, Alexander Ivanko, said.

"This is a slap in the face of the United Nations and the international community, and the Serbs will have to suffer the consequences," Mr. Ivanko said, referring specifically to the carnage in Tuzla. "There is only one option available," he added, and "that is to use air power."

But the Serbs' evident anger and the possibility of a rapid escalation in the violence underscore the political and military risks of the firmer policy adopted this week by the United Nations.

The United States has been pressing for a long time for the bombing of Serbian ammunitions depots, rather than the targets of scant military significance selected by United Nations commanders and NATO in previous raids.

The NATO air raid today, the first since last November, thus bore the hallmark of American planning and prompted a ringing chorus of support from Mr. Clinton and Defense Secretary William J. Perry. It underscored the current United States policy of engaging in diplomatic talks with the Serbian leadership in Belgrade while trying to weaken and isolate the Bosnian Serbs in Pale.

The attack also confirms that the United Nations, faced with the choice of taking a tougher stance or withdrawing from Bosnia, has opted for now for the former course.

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In February 1994, a NATO ultimatum established a zone radiating 12.5 miles around Sarajevo from which all heavy weapons were banned. But that "exclusion zone" has steadily eroded to the point where Sarajevo once again lives in terror and isolation, subjected to regular shelling that has killed dozens of people this month and pushed weary civilians off the street.

Lieut. Gen. Rupert Smith, the British commander of United Nations forces in Bosnia, requested the air raid today after Serbs failed to return four guns taken in recent days from United Nations weapons-collection points. The Serbs had been given until noon local time to give back the weapons.

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A further ultimatum from General Smith requires the Serbs and Bosnian Government forces to hand over or remove all heavy weapons within the 12.5-miles radius of the city by noon Friday.

In the past, tensions between NATO and the United Nations over when and how to bomb have bedeviled relations between the organizations. The United Nations has generally been reluctant to countenance strong action because of the vulnerability of its soldiers on the ground. But in the face of the recent crumbling of the United Nations mission, those difficulties appear for the moment to have been overcome.

Officials traveling with Mr. Perry in Budapest said the mission was carried out by four American F-16s, two American F-18s, two American EF-111 electronic warfare aircraft, one HC-130 refueling aircraft and two American search-and-rescue planes. Two Spanish F-18s, one Dutch F-16 and one French Mirage also took part, they said.

Lieut. Col. Janice Witt, a spokeswoman for NATO's Southern Command in Naples, declined to give details of the aircraft used but said the bombing itself was carried out by six fighter planes.

In the past, the Serbs have responded to even pinprick NATO strikes by taking United Nations personnel hostage. Radovan Karadzic, the Bosnian Serb leader, warned this week that an air strike would turn the United Nations peacekeeping forces into "enemies."

But the American resolve to be forceful in Bosnia has abruptly increased as the possibility has loomed that the United Nations, humiliated and increasingly powerless, might have to withdraw. Such a withdrawal would almost certainly involve the deployment of American soldiers on the ground.

It also coincided with changes in the French Government that may have increased the readiness of the United Nations to call in NATO air strikes. France has the largest contingent of soldiers in Bosnia, but former President Francois Mitterrand, apparently swayed by France's old alliance with Serbia, became increasingly reluctant to confront the Serbs.

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The new President, Jacques Chirac, has appointed a Prime Minister, Alain Juppe, who was among the architects of the successful NATO ultimatum to the Serbs in February 1994. Mr. Juppe has suggested in the past that he sees diplomacy as useless in the Balkans if it is not backed by force. France said today the attack was "fully justified."

But Russia, traditionally sympathetically to the Serbs, sharply criticized the NATO raid and demanded a full explanation from the United Nations Secretary General. It warned that the air attack would only complicate peace efforts.

Adm. Leighton Smith, the NATO commander in charge of the air raid, said he hoped to avoid further bombings. But he added that NATO was ready to strike again if conditions set by General Smith were not met.

Still, it is far from clear exactly what the NATO action will achieve. What Sarajevans really need is an opening of the city -- that is, a breaking of the Serbian encirclement, secure use of a road out and guarantees that the airport will not be closed by Serbian threats.

The United Nations has a mandate to deliver aid to Sarajevo and insure that it is a "safe area" -- enough, under some interpretations, to justify the use of force in insuring that the city is opened to the world. But it is not yet clear how far General Smith will choose to go.