First U.S. Troops to Arrive in Bosnia in Mid-December : Balkans: Officials say peacekeepers will follow advance party one or two days after Dec. 14 signing of accord. The Senate testimony marks first notice of firm date.

The first elements of the 20,000-member U.S. peacekeeping contingent will arrive in Bosnia on Dec. 15 or 16, a day or two after the scheduled signing of the Balkans peace accord in Paris, Clinton Administration officials said Friday.

The announcement was made by Defense Secretary William J. Perry and Gen. John M. Shalikashvili, chairman of the Joint Chiefs of Staff, at hearings before the Senate Foreign Relations Committee and the Appropriations subcommittee for defense.

The two said the deployment will follow an advance party of about 1,465 U.S. military personnel who will be sent to Bosnia-Herzegovina and neighboring Croatia this weekend or early Monday to help set up headquarters facilities, communications and airport equipment.

Shalikashvili also said the Pentagon plans to call up an estimated 3,500 reservists and National Guard troops--mainly specialists in such areas as military police, civil affairs and psychological operations--to help provide backup for the peacekeeping operation.

Not all the reservists will go to Bosnia, he said. Many will be sent to Croatia, and others will go to Germany to fill in for soldiers who normally are stationed there and have been deployed as peacekeepers. The Pentagon hopes to fill most of the call-up with volunteers.

Friday’s testimony marked the first time that the Administration has publicly set a firm date for the start of the deployment.

The U.S. soldiers will join 40,000 North Atlantic Treaty Organization and other troops who will be part of the peacekeeping team, to be known as the Implementation Force, or IFOR.

The announcement came as lawmakers continued to express reluctant support for the deployment, largely because President Clinton has publicly pledged to dispatch U.S. troops to Bosnia, and reneging on that promise would damage American credibility.

Sen. Dianne Feinstein (D-Calif.) joined that group Friday, telling Perry and Secretary of State Warren Christopher at the hearing that she has “come to the conclusion that the risk of not doing [anything] is greater than the risk of doing [something] long-term.”

“I think the cause is noble, and there’s nothing wrong with the strongest democracy in the world being part of a noble cause,” she said in a speech later. “So I will give this 100% support.”

Meanwhile, Assistant Secretary of State Richard Holbrooke, seeking to assuage Congress’ concerns that U.S. troops might become mired down in Bosnia, said the peace accord--to be signed Dec. 14--had been crafted to avert “the Vietmalia syndrome”--the disasters experienced in Vietnam and Somalia.

In a meeting with a small group of reporters, Holbrooke, who was chief mediator at the Dayton, Ohio, peace talks last month, also rejected a reported offer by the Bosnian Serbs to release two French pilots captured this summer if the peace pact were renegotiated.

“That is not going to happen,” he said.

Congressional support for the Bosnia deployment, while grudging, has been growing since Monday night, when Clinton delivered a nationally televised address to make his case for sending the troops.

On Thursday, Senate Majority Leader Bob Dole (R-Kan.) announced that he too will support the President’s deployment plan and will begin drafting a resolution to that effect for the Senate to take up next week.

Republican leaders in the House have acknowledged that they do not have the votes to block Clinton from dispatching the troops but are split over whether to schedule a vote on a resolution of their own. A decision is expected early next week.

Dole, the front-runner for the GOP presidential nomination, threatened Friday to withdraw his support for the deployment if Clinton does not lay out a more “concrete, detailed and effective” plan for arming and training the Bosnian military--an issue he has been stressing for several months.

That threat may calm conservatives who had been critical of his support for the deployment, but it is considered unlikely that Dole will ultimately oppose the operation.

As they did in earlier testimony Thursday, Perry, Christopher and Shalikashvili spent most of their time before the Foreign Relations Committee trying to assure members that the deployment is crucial to the peace accord and that the risks to troops will be limited.

“In Bosnia, we have a fundamental choice,” Christopher said. “If the United States does not participate, there will be no NATO force. And if there is no NATO force, there will be no peace in Bosnia, and the war will reignite.”

Perry told the panel that U.S. troops will move in rapidly by rail from their bases in Germany to a staging area in Hungary and then enter Bosnia in armored personnel carriers and trucks so that “they will be able to take care of themselves” if they run into trouble.

Shalikashvili said the U.S. contingent will be backed up by several thousand other American military personnel as support forces--including 5,000 logistics troops in Croatia, 3,000 in Hungary, 1,700 fighter pilots in Italy and about 7,500 on U.S. warships.

Both men also expressed confidence that, barring some unforeseen developments, U.S. troops should be ready to return home in about a year. And they said they expect to hammer out a disarmament agreement among the warring parties by that time.

The U.S. portion of the peacekeeping operation is expected to cost about $2 billion--including $1.2 billion for deploying and maintaining the ground troops, $500 million for logistics support and $300 million for continued air support.

Meanwhile, key Republican lawmakers Friday challenged Clinton’s assertion a day earlier that they had agreed to finance the cost of the Bosnia deployment in exchange for his decision not to veto the defense appropriations bill, saying that he will have to ask Congress for more money.

Clinton cited the agreement when he announced his decision late Thursday. But House Appropriations Committee Chairman Bob Livingston (R-La.) said Friday that there had been no such deal.

“Any request that the President makes . . . we will consider,” he said.

Times staff writer Stanley Meisler contributed to this report.