Accord Is Reached on Integrating Russian Troops in Kosovo Force
Russia and United States sign military agreement that integrates 3,600 Russian troops into Kosovo peacekeeping force, dividing them among three of five sectors led by NATO countries; accord comes after three days of grueling negotiations, breaking tense stalemate over Russia's role in Kosovo; control of airport is to be shared: Russian commanders will be in charge of ground operations, while NATO will oversee air traffic control; Russian negotiators had originally demanded separate Russian sector, as had Pres Boris N Yeltsin; photo (M)