Clinton Offers Troops for Bosnia Pullout : Balkans: Up to 20,000 U.S. soldiers could assist if peacekeepers evacuate. President pledges to consult Congress before deploying forces to nation for first time.

President Clinton formally offered Thursday to send up to 20,000 U.S. ground troops to help evacuate the U.N. peacekeeping force in Bosnia-Herzegovina if the allies decide to withdraw in the face of increased harassment and hostage-taking by nationalist Serbian forces there.

Pentagon officials said the United States would probably supply between 40% and 50% of an allied evacuation force of up to 45,000 troops. The U.S. military is also likely to provide the bulk of the air- and sea-lift for the operation.

The mission would mark the first time the United States has sent ground troops to Bosnia.

U.S. officials emphasized that the President’s decision involved only a commitment “in principle,” and they said the Administration would insist on approving any evacuation plan in advance and consulting with Congress.

The operation would be conducted by the 16-country North Atlantic Treaty Organization and almost certainly would be under the command of an American general or admiral.

A senior U.S. official said the United States would contribute “a substantial part” of the total NATO force--which he said could involve up to nine brigades, complete with tanks and heavy weapons. But he said no firm decisions had been made on how many troops may be involved.

However, some of those familiar with the operation said an estimate of between 15,000 and 20,000 U.S. troops would be “a good working number” for such a venture. While some would come from U.S. bases in Europe, most would be from bases within the United States.

Although U.S. officials stressed that the allies have not yet decided to withdraw any peacekeeping troops, NATO strategists are in the early stages of drafting military plans for the evacuation. They are working on an array of contingency proposals, from a simple loading operation involving fewer troops to a full-scale extraction under heavy fire. Allied defense ministers will meet to review the plans next week.

Officials said Clinton’s announcement was designed to reassure France, Britain and other U.S. allies that the United States will help evacuate their troops, despite the recent controversy here over the use of American forces in peacekeeping-related missions.

U.S. officials delivered a similar message to the allies privately last week but apparently failed to quell some doubts.

Policy-makers hope that “clearing up any ambiguity” publicly will help heal the rift in NATO and persuade some member countries to leave their troops there longer.

Congressional Republicans appeared ready to accept the notion of U.S. participation in such an evacuation, but they served notice that they would insist that Clinton seek formal authorization from Congress before actually committing U.S. troops.

Incoming Senate Majority Leader Bob Dole (R-Kan.) also noted pointedly that withdrawal of U.N. peacekeepers would clear the way for lifting the arms embargo against the Bosnian Muslims and carrying out more aggressive NATO air strikes, which GOP senators have endorsed.

The Administration had advocated both policies over the months, but was unable to put them into effect because Europeans feared their peacekeeping troops would then become targets of stepped-up retaliation by the Serbian nationalists.

However, a senior U.S. official hinted Thursday that the Administration may resume pressing the allies to lift the embargo and to intensify NATO air strikes against the Serbian nationalists if the U.N. peacekeeping troops are forced to withdraw.

On the Democratic side, Sen. Claiborne Pell (D-R.I.), outgoing chairman of the Senate Foreign Relations Committee, said he was disturbed that Clinton had made the troop offer. Pell said he is opposed to any use of U.S. ground troops in Bosnia.

Reaction from the United States’ NATO allies was muted.

Britain welcomed Clinton’s offer but emphasized that a pullout of U.N. peacekeeping forces still was not imminent. French officials did not comment on the decision.

In Ottawa, Canadian Prime Minister Jean Chretien said his country’s peacekeeping troops will remain in Bosnia at least until their current U.N. mandate expires in March, despite the increasing harassment they are suffering at the hands of nationalist Serbs. He rejected calls to withdraw them more quickly.

There are now about 24,000 U.N. peacekeeping troops in Bosnia, mostly French, British, Jordanian and Pakistani. Outside analysts have estimated that evacuating the peacekeepers and several thousand U.N. civilian personnel would take between 20,000 and 45,000 NATO troops.

Experts also said the evacuation could take anywhere from several weeks to several months, depending on how vigorously Serbian nationalist--and possibly even Bosnian Muslim--forces try to impede the withdrawal. The allies have 8,000 vehicles in Bosnia and many tons of supplies.

A senior Pentagon official said preliminary discussions with both factions had indicated that neither side would try to harass or block an evacuation effort if the U.N. force decides to withdraw, but he conceded that that could change once an operation got under way.

Plans for possible evacuation are expected to be a major topic next week, when NATO defense ministers, including U.S. Defense Secretary William J. Perry, meet in Brussels to discuss the situation in Bosnia.

U.S. officials said Perry and British Defense Minister Malcolm Rifkind will host a breakfast Wednesday for defense ministers of countries that have troops on peacekeeping duty in Bosnia to review the NATO plans and sound them out on such an operation.

They said the ministers are also expected to discuss what policies should be pursued after any withdrawal, which presumably will include the questions of whether to lift the arms embargo against the Muslims and possibly to step up military action against the Serbs.

“We will . . . certainly be discussing this with a view toward finding a common position,” an official said.

Although the Administration has pledged before that it will not send ground troops to Bosnia for ordinary peacekeeping duty, it has consistently said it will deploy American forces both to help enforce any firm peace accord or to evacuate U.N. troops in an emergency.

There was no immediate indication how the Serbian nationalists in Bosnia would react to the President’s announcement. Analysts said the rebels’ reaction is likely to be heavily influenced by what role they expect the United States to play next.

If they fear that the evacuation of U.N. troops will lead to a lifting of the arms embargo, they might attack U.S. forces with a vengeance. Bosnian Serb leader Radovan Karadzic has repeatedly boasted that American troops would be sent home in body bags if they intervened.

But the deliberate humiliation of U.N. troops in recent weeks suggests that the Serbs have calculated that they could conquer what is left of Bosnia once the U.N. forces are out and before the Muslim-backed government could obtain enough arms to launch a successful counteroffensive.

The evacuation effort could also be impeded by Bosnian Muslims, particularly if they fear they would be overrun by the Serbs. At the same time, if the Muslims believe the arms embargo will be lifted, they may help the United Nations.

Times staff writer Carol J. Williams in Zagreb, Croatia, also contributed to this report.

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