(L-R) British Prime Minister Gordon Brown, U.S. President Barack Obama and French President Nicolas Sarkozy attend the mourning ceremony to tribute to the NATO military personnel for service in operational theatres, in Strasbourg, France, on April 4, 2009, after crossing German-French border bridge, Passerelle Bridge, which connected German city Kehl and French city Strasbourg. Leaders of NATO member states held a symbolic ceremony on the French-German border on Saturday to celebrate the 60th anniversary of the military alliance and the return of France as a full member. [Wu Wei/Xinhua]