NATO Issues Ultimatum to Serbs Ringing Enclave : Bosnia: Alliance threatens air strikes unless rebels withdraw 2 miles from Gorazde’s center by 3 p.m. today.

Reacting to mounting international outrage, the NATO alliance Friday delivered an ultimatum to Bosnian Serb forces to stop their attacks on the besieged city of Gorazde or face immediate air strikes against a range of military targets.

“The situation demands action,” NATO Secretary General Manfred Woerner told reporters.

Hundreds of civilians have died in recent days as the defenseless city--one of six areas in war-torn Bosnia-Herzegovina that the United Nations declared “safe havens”--has been subjected to relentless Serbian artillery, mortar and tank bombardment.

That shelling continued Friday for hours beyond announcement of the NATO ultimatum, killing 99 people and wounding nearly 300, according to trapped city officials and relief workers communicating via ham radios.

Late Friday, Yasushi Akashi, U.N. special envoy to the former Yugoslav federation, said the Serbs had agreed to a cease-fire around Gorazde beginning at noon today (3 a.m. Pacific time). But dozens of such agreements have gone unfulfilled or lasted mere minutes.

In addition to the immediate cease-fire, ambassadors to the 16-nation North Atlantic Treaty Organization also demanded:

* That all Bosnian Serb forces withdraw at least 1.9 miles from the Gorazde city center by one minute past midnight Sunday morning local time (3:01 p.m. today Pacific time). Failure to do so could prompt a NATO attack.

* That a 12-mile military exclusion zone from the Gorazde city center be established by one minute past midnight Wednesday morning (3:01 p.m. Tuesday Pacific time). Any heavy weapons remaining in this zone would be subject to air strikes. (A small section of Serbia proper that lies within the 12-mile zone was specifically excluded, however.)

* That U.N. peacekeeping forces, humanitarian relief convoys and medical assistance teams be able to enter Gorazde unimpeded and that medical evacuations are permitted.

NATO also declared that, effective immediately, firing by Bosnian Serb forces into four other U.N.-designated safe areas--Bihac, Srebrenica, Tuzla and Zepa--or any massing of troops within a 12-mile radius of those cities would automatically make the areas military exclusion zones, exposing Bosnian Serb weapons and other military assets there to air strikes.

Calling the measures “some of the most far-reaching decisions in the history of our alliance,” Woerner warned that “it is now up to the Bosnia Serbs to heed these demands or face the most serious consequences.”

Wording of the ultimatum, which threatens air strikes against Bosnian Serb “heavy weapons and other military targets” within Gorazde’s exclusion zone, constitutes both a significant broadening of NATO options for military action in Bosnia and, at least potentially, a deeper involvement in the war.

The language would also appear to give the alliance a degree of the flexibility it had wanted in order to attack a variety of Bosnian Serb targets, including ammunition dumps, military command posts and communications centers in addition to the weapons themselves.

Until now, NATO air strikes in Bosnia have been limited to attacks on specific Bosnian Serb heavy weapons that have threatened U.N. peacekeepers.

“This is not tit-for-tat targeting,” U.S. Ambassador to NATO Robert Hunter said. “There’s a broader targeting set now than before. Just about anything that has a war-making potential is in my mind fair game.”

However, the alliance failed in its attempts to streamline an unwieldy chain of command that in the past has required such intense coordination with the United Nations that it has become an embarrassment.

While the commander of NATO forces in Southern Europe, U.S. Adm. Leighton Smith, can now initiate a call for attacks on Bosnian Serb targets in the Gorazde area from his headquarters in Naples, Italy, he must have the agreement of the commander of U.N. forces in Bosnia, Lt. Gen. Michael Rose, to do so. And Rose, a Briton, cannot act without permission of U.N. Secretary General Boutros Boutros-Ghali’s special envoy, Akashi.

In one instance last month, more than five hours elapsed from the time a group of French U.N. peacekeepers requested NATO air support to the time authorization was finally received from Akashi. By then, poor visibility prevented the air attack. NATO officials later said their aircraft could have reacted within minutes.

In Washington, both Pentagon and State Department officials expressed confidence Friday that the chain of command would not impede rapid response. Pentagon officials said they expected Boutros-Ghali would explicitly approve the first air strike and that after that, NATO forces would have the latitude to pursue operations without such explicit approval.

“We have no reason to believe there will be any difference of opinion” between Boutros-Ghali and NATO planners, one Pentagon official said.

Pentagon officials said more than 200 NATO aircraft are ready to carry out the alliance’s new threats “at any time.” The U.S. carrier Saratoga, with 18 warplanes, is in the Adriatic Sea, and 40 other warplanes, ranging from F-15E Strike Eagles to the venerable O/A-10 attack aircraft, are scattered throughout Europe within striking distance of Gorazde.

But a senior U.S. military official warned that any air attacks will likely exact a toll on NATO air crews. Unlike the situation around Sarajevo, he said, potential Bosnian Serb targets around Gorazde are scattered throughout populated and built-up areas and are frequently hidden under low cloud cover.

“It means you have to get fairly close to your business,” he said, adding that NATO air crews will be more vulnerable to antiaircraft fire. Bosnian Serb forces shot down a British Harrier jet last weekend with a heat-seeking missile.

Hunter, the U.S. ambassador to NATO, described the Gorazde ultimatum as a U.S. idea that was sold to the United States’ allies within the course of prolonged meetings Friday.

“This is a Clinton initiative, not a NATO initiative,” Hunter said. “We brought it in at 9 o’clock this morning and by 6, we had gotten agreement.”

In Washington, officials said that some in the Administration had wanted to authorize air strikes against strategic targets anywhere in Bosnia. Officials said the Europeans insisted that they be limited to targets directly involved in attacks on safe areas. But they did allow for the possibility of gradual escalation of the target list.

“There are 15,000 peacekeeping troops on the ground there,” a European diplomat in Washington said. “The nightmare for all the countries that have sent them is to find that they have been turned into targets, whether of snipers or hostage-taking.”

Nations with U.N. peacekeepers on the ground, including France, Britain and Canada, were reportedly reluctant to give NATO more freedom from U.N. control in determining specific targets and the timing of attacks.

Bosnian Serbs have threatened reprisals against these peacekeepers if NATO follows through with threats to intensify its air attacks. Friday, they blocked a U.N. convoy from returning to Sarajevo after it had failed to reach Gorazde on Thursday; 141 U.N. peacekeepers were thus vulnerable to being taken hostage.

U.S. and British officials said they were withdrawing nonessential personnel and diplomats’ families from their embassies in the Yugoslav capital, Belgrade, for fear of possible reprisals.

Hunter said Clinton decided late Thursday to press the ultimatum after Administration officials believed that Bosnian Serb forces were accelerating their bombardment of Gorazde in an attempt to capture the city before NATO could formally respond to Boutros-Ghali’s latest request for alliance help.

That request, contained in a letter last Monday, was carefully restricted to attacks on Bosnian Serb heavy weapons firing into the city.

Friday’s ultimatum, however, draws on an earlier NATO mandate given last August to act to prevent the strangulation of six safe areas and wide-scale interference with humanitarian assistance.

It is the second such set of demands issued by NATO to Bosnian Serb forces this year and is modeled after the initial one, made last Feb. 9, which brought about a cease-fire and a 12-mile exclusion zone around the Bosnian capital, Sarajevo, also a designated safe area.

In general, the Bosnian Serbs have respected the Sarajevo ultimatum, and a shaky peace has held there for the last two months.

Friday’s ultimatum appeared to run the risk of straining ties between Russia and the West.

Woerner said Moscow was also immediately informed of the NATO ultimatum, and he stressed the need for Russian involvement in any negotiated settlement of the conflict.

He also noted consultations between Russian and some NATO member states during the run-up to Friday’s meeting.

Russian Foreign Minister Andrei V. Kozyrev, speaking Friday before NATO ambassadors reached a decision, warned that NATO air strikes would simply escalate the violence.

“The NATO decision, if it is adopted, will exceed the limits of the broadest interpretations of the U.N. Security Council resolutions,” he said. “We have not done everything to help the Serb side make a choice in favor of peaceful settlement.”

Another Russian diplomat, Grigory Karasin, announced that Russia was ready to withdraw its U.N.-controlled peacekeeping troops from Bosnia if they become endangered by new NATO air strikes. He did not make it clear whether Russia might act unilaterally in such a pullout.

Times staff writers Melissa Healy, in Washington, and Richard Boudreaux, in Moscow, contributed to this report.