"As NATO's long involvement in Afghanistan concludes, the renewed emphasis on Russia and Europe is also likely to delay the alliance's efforts to turn itself into a global actor, able to deal with threats like terrorism and cyberwarfare."
LONDON — Russia's annexation of Crimea has suddenly revived the North Atlantic Treaty Organization's central role as a counterweight to Moscow, and with it questions about the alliance's options and ability to act.
Vice President Joseph R. Biden Jr. swept into Poland and the Baltic nations on Tuesday with a message of reassurance that their membership in NATO carries the protection of the United States. But given deep Western reluctance to use military force in response to Russia's aggression, it remains unclear what the alliance's commitment to collective security means for Ukraine and other nonmembers should President Vladimir V. Putin continue to try to expand Moscow's influence in the former Soviet bloc.
Ian Bond, the director of foreign policy at the Center for European Reform, a London-based research group, said that "Putin has just given NATO something to do, but the question is whether NATO is up to it." It is now crucial to deter further moves by Mr. Putin, he said. "If Russian forces move into eastern Ukraine," he said, "what would NATO do?"