President Barack Obama meets with NATO Secretary General Anders Fogh Rasmussen in Brussels, Belgium, Wednesday, March 26, 2014. Obama is on a one day trip to Belgium to shore up commitments he received from allies in The Hague, Netherlands, to reassure Eastern Europeans members of NATO that the alliance will stand by them and to make a larger point about European security a quarter-century after the fall of the Iron Curtain. (AP Photo/Pablo Martinez Monsivais) (AP Photo/Pablo Martinez Monsivais)
North Atlantic Treaty Organization (NATO) Secretary General Anders Fogh Rasmussen listens to a question while speaking about the future of NATO at The Brookings Institution in Washington, Wednesday, March 19, 2014. As it steels itself against westward Russian advances, NATO may find itself stretched too thin to maintain a broad military mission in Afghanistan by its member states beyond this year. U.S. officials said having to divert troops and resources, if not withdrawing completely, from Afghanistan to secure NATO states would be an unintended casualty of the West’s new focus on containing Moscow. (AP Photo/Jacquelyn Martin)
North Atlantic Treaty Organization (NATO) Secretary General Anders Fogh Rasmussen speaks about "The Future of the Alliance: Revitalizing NATO for a Changing World," Wednesday, March 19, 2014, at The Brookings Institution in Washington. As it steels itself against westward Russian advances, NATO may find itself stretched too thin to maintain a broad military mission in Afghanistan by its member states beyond this year. U.S. officials said having to divert troops and resources, if not withdrawing completely, from Afghanistan to secure NATO states would be an unintended casualty of the West’s new focus on containing Moscow. (AP Photo/Jacquelyn Martin)