NATO’s Risk: Escalation or Humiliation : Bosnia: Latest action against Serbs ‘ups the ante,’ experts say. Some worry situation could spin out of control.

The NATO allies’ latest air strikes in Bosnia could force them to confront a choice they have shunned for months: whether to gird U.N. forces for full-scale combat or pull them out entirely and abandon the country to civil war, military analysts say.

Although Western officials portray the latest air attacks as only a tit-for-tat response to Bosnian Serb violations, experts say they actually amount to a new high-risk strategy that could quickly escalate into serious fighting--and additional casualties for U.N. forces.

There is no doubt that this time the allies’ threat is more serious. Instead of the usual “pinprick” attacks on an abandoned Serbian tank or runway, they have been hitting at militarily significant targets: ammunition bunkers maintained by the Bosnian Serb army.

They struck near Pale, the stronghold of the Serbian nationalist leadership. After the Serbs shelled Tuzla to retaliate, the allies quickly returned for a second hit. And by all accounts, they are prepared to continue the attacks for some time.

But the fear is that the West has been so timid before that it has lost all credibility with the Serbs. The rebels have taken more than 200 U.N. peacekeepers hostage, including dozens seized Saturday.

“It’s a test of wills right now, but each step that the two sides take ups the ante significantly,” said Bernard E. Trainor, a retired Marine Corps lieutenant general now at Harvard University’s Kennedy School of Government. “They [the allies] are risking escalation--or humiliation.”

That view is also held by Don M. Snider, a military analyst at the Center for Strategic and International Studies, a defense-monitoring group. Because the allies have wavered before, “it’s not clear that the Serbs will respond to the latest use of force,” he said. “It could very quickly get out of control.”

The tougher strategy was engineered by the Clinton Administration, which has been frustrated over the Serbs’ recalcitrance.

U.S. officials have been pressuring the allies for weeks to prod U.N. leaders into agreeing to more “robust” NATO air strikes.

The Administration fears that its allies might soon withdraw their peacekeeping forces if the Serbs do not stop harassing them. Not only would a pullout intensify the civil war, it would require the help of as many as 25,000 U.S. ground troops--a situation Clinton wants to avoid.

For months, NATO strategists have been working on a series of military contingency plans to use if the situation in Bosnia-Herzegovina does not improve. The choice was either to reinforce existing U.N. forces there--equipping them for full-scale combat--or to evacuate them. Analysts say the latest round of air strikes is a last-ditch effort to stave off a pullout of allied peacekeeping forces by stepping up the military pressure, at least for the near term, in hopes that the Serbs finally will get the message and make peace.

“We are at a turning point,” NATO Secretary General Willy Claes told reporters at a news conference at the alliance’s Brussels headquarters on Friday. “The international community cannot accept any longer to be humiliated.”

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Allied leaders say that this time the West has the resolve to keep up the pressure, even in the face of Serbian retaliation. They say the air strikes will continue even as U.N. troops are being held hostage.

U.S. Defense Secretary William J. Perry acknowledged that the allied shift entails certain dangers, but he said the risk of allowing the Serbs to continue shelling key U.N.-protected enclaves such as Sarajevo and Tuzla is far greater.

“I believe [the NATO air strikes] will be effective and, in time . . . will achieve the desired results,” Perry said. “But I do not expect that result--namely the stopping of the shelling--to occur immediately.”

Claes told reporters that the allies had fully considered the likelihood of rebel Serb retaliation before they agreed to order the attacks.

“We are not naive,” he said. “We did not expect a telegram of thanks from [Bosnian Serb leader Radovan] Karadzic.”

Even so, some analysts are wary. Barry Posen, policy analyst at the Massachusetts Institute of Technology, points out that the Serbs have acquired considerable skill at pushing the allies to the brink and gaining ground in the process.

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By contrast, the West has shown that it is likely to turn from any conflict that threatens to produce serious casualties. In Somalia, the United States pulled out its forces after a firefight cost 18 U.S. lives. And it has refused to send peacekeeping troops to Bosnia.

As a result, many foreign policy experts believe that, if the latest allied effort fails, the West could find itself at a point of no return--with no way to get the Bosnian peace talks back on track and no way to enable the U.N. peacekeeping forces to stay.

If that proves to be the case, peacekeeping forces will have to be evacuated under hostile conditions, at great risk to U.N. troops and to the Americans who presumably would be deployed to help rescue them. Casualties would probably be high.

A pullout could also seriously injure the North Atlantic Treaty Organization. Europeans, who have bitterly resented Clinton’s continual push for more air strikes when the United States has no troops of its own on the ground, almost certainly would hold Washington partly to blame for any casualties.

Anthony H. Cordesman, a military affairs specialist at the Center for Strategic and International Studies, warned that “with each step of escalation, you find yourself being pushed into the position of having to take sides and watching the peacekeeping mission collapse.”

At this point, Cordesman said, “I’m afraid that the only light at the end of the tunnel is on the way out.”

Times staff writer Tyler Marshall in Brussels contributed to this report.