WASHINGTON -- Asserting that the mission justifies the risk of American casualties, President Clinton's top national security advisers yesterday resisted bipartisan pressure to seek congressional approval before deploying U.S. troops to Bosnia as peacekeepers.
The officials said that the deployment of up to 20,000 U.S. troops -- scaled back from earlier estimates of 25,000 -- to a NATO peacekeeping force of 60,000 could involve the call-up of 2,000 to 8,000 reservists.
The reservists' duties would include engineering and civil liaison in Bosnia, transport and supply support in Croatia and Italy, and medical backup in Germany, according to a Pentagon official. It was not known from which units the reservists would be drawn.
But Secretary of State Warren Christopher, Defense Secretary William J. Perry and Army Gen. John M. Shalikashvili, chairman of the Joint Chiefs of Staff, pledged during their testimony before two Senate committees that American troops will be fully capable of defending themselves.
"This NATO force will be the biggest, toughest and meanest dog in town," said Mr. Perry. "If attacked, it will bring a large hammer down on [the attackers] immediately."
Such assurances aside, Republicans and Democrats on the Senate Foreign Relations and Armed Services committees pressed the Clinton aides for a commitment to bring the issue to Congress before actually deploying the U.S. troops, perhaps as early as next month.
Republican Sen. Strom Thurmond of South Carolina, the Armed Services chairman, said it would be "pure folly" for Mr. Clinton not to seek congressional approval for the military deployment.
Sen. Jesse Helms, a North Carolina Republican and chairman of the Foreign Relations Committee, told the officials: "I cannot and I do not and I will not support sending American soldiers to fight and to die for the sake of an agreement not yet reached, which may offer no more than the promise of a brief pause while all sides prepare for the next round of Balkan wars."
Faced with a chorus of demands for greater involvement by lawmakers, Mr. Perry and Mr. Christopher said only that Mr. Clinton would "welcome" congressional support for the mission.
They steadfastly refused to endorse repeated suggestions that he should seek the lawmakers' approval.
But Mr. Christopher acknowledged: "It is vital that the administration, Congress, and, most important, the American people find common ground on the need for American leadership."
The two Cabinet members stressed that the deployment of American troops as part of a NATO peacekeeping force was in the nation's vital interest.
Their rationale: U.S. interests would be served by preventing the spread of war in the Balkans and ensuring peace and stability in Europe. U.S. leadership of NATO also is at stake, they said, insisting that the United States could not walk away from the mission and retain its primacy within the alliance.
Mr. Christopher said the Bosnian government would not sign a peace agreement unless the United States and NATO were committed to policing it.
The administration, which plans to send in troops only if a peace settlement is signed, is preparing to convene peace talks in the United States this month. It will work out details of how large an American force will be needed and try to find a formula to allow the Russians, who refuse to serve under NATO command, to be involved in the mission.
The U.S. deployment is slated by the administration to last no more than a year.
The peace plan calls for establishing military stability in Bosnia-Herzegovina. The administration hopes to achieve this by arms control, persuading the Bosnian Serbs to reduce their heavy weapons to the level of the weaker Bosnian government forces.
If the Serbs refuse, Mr. Perry told lawmakers, the administratiowould seek an end to the international arms embargo on the the warring factions that would allow the United States to equip and train the Bosnian army to the level of the Serbs.
Sen. James M. Inhofe, an Oklahoma Republican, recalled 18 U.S. Rangers being killed by rebels in Somalia and said: "I'd like to have any one of you tell me, if we're going to have hundreds of young Americans dying over there, is the mission justification for their deaths?"
Mr. Perry replied: "Yes. The U.S. has vital political, economic and security interests in Europe."
In Sarajevo, the Bosnian government warned yesterday of trouble if Serbs do not soon restore water to the city, a threat apparently designed to move the Bosnian capital's fate to center stage in coming peace talks.
The Serbs want part of Sarajevo in any peace settlement, and have not fully lifted their siege of the capital. The Muslim-led government says the city cannot be divided, and so far Western powers have backed that position.
But there also were signs of progress.
Government officials and Bosnian Serb military leaders were meeting at Sarajevo airport for a second day to negotiate an exchange of prisoners of war.
And the United Nations succeeded in getting a convoy through to the beleaguered government-held enclave of Gorazde in eastern Bosnia after Serbs had blocked the road in defiance of the cease-fire.