Turning up the heat on the Bosnian Serbs,President Clinton announced that he has decided to allow U.S. troops to participateif UN forces mount a rescue raid into Bosnia to recover the nearly 400 peacekeepers held hostage there. The tactic may be working: the Serbs said today that they are willing to begin talks immediately, but are not yet willing to free the hostages before talks begin. The President stressed thatU.S. troops would be deployed only at NATO request, and only as temporary support. Though Clinton said he would consult Congress before taking any action, Republicans objected that he should have consulted Congress before taking his new position. As far as sending in troops, Sen. John McCain (R-Ariz) bluntly said: "It's not consultation with Congress that would be required, it would be the approval of Congress that would be required." ButTIME Washington correspondent J.F.O McAllisterobserves that Congress usually makes a big stir and then goes along with the President because "they want him to take the heat."