AF Chief Doubts Bosnia Raid Risks : Balkans: He contradicts warnings by other military leaders on attacking Serbs. Senate testimony gives White House boost as it assesses further involvement.

The nation’s top Air Force general broke ranks Wednesday with other high-level military leaders over the dangers of air strikes in Bosnia-Herzegovina, asserting that U.S. planes could attack Serbian forces with “virtually no risk” to American pilots.

The assessment by Gen. Merrill A. McPeak, the Air Force chief of staff, directly contradicted recent warnings by other members of the Joint Chiefs of Staff that launching air strikes in Bosnia would be risky and could draw the United States into long-term military involvement.

It also provided political help for the White House, which has been straining under admonitions from military leaders, key U.S. allies and some members of Congress who have cautioned the President against further military involvement in the region.

President Clinton said Wednesday that he continues to believe that the United States must take tougher action to stop the fighting in Bosnia, despite the warnings from Congress and the military. “I still believe the United States has to strengthen its response,” he said.

In related developments Wednesday:

* Islamic states pledged $68 million in emergency aid to Bosnia, well short of the $260 million the war-torn state had requested.

* Yugoslav President Dobrica Cosic insisted that Serbs are not responsible for the Balkan crisis, and he described the tightening of U.N. sanctions against his country as wholly unjustified.

* The North Atlantic Treaty Organization agreed to blockade Yugoslavia’s coast, and one official said allied warships in the Adriatic Sea would shoot if necessary to stop vessels trying to carry banned goods to Serbia.

* France’s defense minister threatened to withdraw 5,000 French peacekeepers from the former Yugoslav republics unless their mission is better defined.

At the White House, Communications Director George Stephanopoulos said the President probably will decide on possible U.S. action in Bosnia by the end of the week and then would consult with allies. He reiterated that Clinton would not order any new action without allied support.

Another Administration official said Clinton appears to be leaning toward seeking an end to the international arms embargo against Bosnia, coupled with limited air strikes to give the Bosnian Muslims time to arm themselves. “But he clearly hasn’t made the decision yet,” the official said.

Other options before the President include punitive air strikes designed to “send a message” to the Serbs or actually to knock out Serbian artillery batteries, officials said.

Zalmay Khalilzad, a former Defense Department policy planner, said in an interview that U.S. military leaders with whom he has talked favor lifting the arms embargo and oppose launching air strikes against the Serbs, even though the former would pose some tactical risks as well.

Many U.S. allies have voiced opposition to stepped-up military action.

On Wednesday, a top aide to Prime Minister John Major said Britain is anxiously urging the Administration not to lift the arms embargo on the Bosnian Muslims, partly for fear that it would spark Serbian reprisals against British peacekeeping troops.

“Europeans are against it,” he said. “It is the worst option.”

In Brussels, British Field Marshal Richard Vincent, chairman of NATO’s military committee, warned that the alliance should not begin any military operation until political leaders define their goals in Bosnia more clearly.

McPeak’s comments, delivered in testimony before a Senate Appropriations subcommittee, underscored the deep divisions that the new Administration has encountered trying to shape a Bosnia policy.

Only a day before, Adm. David E. Jeremiah, vice chairman of the Joint Chiefs of Staff, warned that air attacks and other military operations in Bosnia would be difficult and could heighten civilian casualties and risk the loss of American pilots.

Even as McPeak was testifying, three senior military officers who have been nominated for top staff jobs with the Joint Chiefs told the Senate Armed Services Committee they have deep reservations about increasing U.S. military involvement in the region.

Army Lt. Gen. Barry R. McCaffrey, named to be the new strategic planner for the Joint Chiefs, told the panel that he sees “no military solution” to the Bosnian situation.

Marine Corps Maj. Gen. John J. Sheehan said that if air power is used, “I have a very difficult time answering questions as to what is Chapter 2 in that strategy, as to how we declare victory and walk off this battlefield” without sending in ground forces.

And Air Force Maj. Gen. Michael E. Ryan said that air strikes alone would not work unless the Serbs are convinced that the allies would be sending in ground troops if the bombings did not succeed.

But McPeak declared, “Give us time and we will order (strikes) on every one of those artillery positions and put it out of business.”

McPeak tempered his assessment, however, with a warning that while there is little doubt that the air strikes could be carried out, there is no guarantee that bombing the Serbs would help end the fighting in Bosnia.

At a conference of the Organization of the Islamic Conference in Karachi, Pakistan, member states expressed solidarity with Bosnia’s Muslims and pledged $68 million to their cause but stopped short of pledging arms.

In Brussels, a NATO spokesman said the blockade of Yugoslav waters would start “as soon as possible” but first had to be coordinated with the Adriatic flotilla operating under the Western European Union, a nine-nation defense group.

And in Paris, Defense Minister Francois Leotard told the National Assembly that France’s government wants clearer rules for the peacekeepers’ operations and command structure and for financing the peacekeeping mission.

“If these questions aren’t resolved, we will withdraw all or part of our forces,” he said.

Times staff writers William Tuohy in London and Doyle McManus in Washington contributed to this report.