NATO leaders gathered here Friday to celebrate the 60th anniversary of [the] alliance ... also must face the harsh reality that NATO's first military mission outside Europe is failing in a way that risks fracturing the alliance. Obama, [by] increasing American troops in Afghanistan to some 68,000 by the end of the year from 38,000 today, is also likely to significantly Americanize an operation that in recent years had been divided equally between American troops and allied forces. By year's end, American troops will outnumber allied forces by at least two to one. His NATO allies are giving ... him very few new troops on the ground, underlining the fundamental strains in the alliance. The allies will offer more funds but no more than several thousand new personnel members, according to alliance military planners. Many of those will not be soldiers, but police trainers to meet a central pillar of the president's new Afghan strategy, which focuses on an expansion of Afghan security forces. But even for the small numbers of European combat reinforcements, check the fine print: Nearly all will be sent to provide security for Afghanistan's elections this summer, and will not be permanently deployed. Defense Secretary Robert M. Gates and his British counterpart, John Hutton, have publicly warned that the performance of some European troops demonstrates that NATO risks slipping toward a two-tiered alliance. In that event, it would be divided between those that can and will fight, like Britain, Canada, France and Poland, and those that cannot or will not because of public opinion at home.