BRUSSELS -- NATO foreign ministers, burying differences on Bosnia, reaffirmed their commitment Thursday to a strong, united alliance under American leadership.


"A strong trans-Atlantic partnership and a continued substantial presence of United States forces in Europe ... are fundamental not only to guarantee the alliance's core functions, but also ... to contribute effectively to European security," the ministers said in a joint statement.


NATO Secretary-General Willy Claes told reporters the meeting took place at a time when the alliance was being tested like never before.


"It has been in trouble before, but has always bounced back. This it has done again," he said.


"Only by staying together can we meet this test," he added.


The NATO dispute on Bosnia has centered on NATO's failure to protect the UN-designated safe haven of Bihac in the face of a Bosnian Serb onslaught. European leaders have accused the United States of sabotaging peace efforts by siding with Bosnia's beleaguered Moslems, while U.S. congressmen say European faintheartedness has blocked NATO air strikes to halt Serb attacks.


U.S. Secretary of State Warren Christopher has brought with him a plan to try to revive the Bosnian peace talks that goes a long way toward answering European insistence that only a diplomatic solution, not a military one, can deal with the present crisis.


The plan will be put to a meeting of the so-called contact group on Bosnia, comprising the United States, Russia, Germany, France and Britain, in Brussels on Friday.


Dubbed "Plan B,"the main thrust is to give clearer incentives to Serbian President Slobodan Milosevic to bring his kin in Bosnia and Croatia into line, according to diplomats.