PREVIEW-Afghanistan shows challenges for more global NATO

(Reuters) - The United States is pushing NATO to shoulder more global burdens but the alliance's Afghan deployment illustrates the challenges of getting the 26-nation group to project its power beyond its borders. Ahead of the North Atlantic Treaty Organization's Nov. 28-29 summit in Riga, U.S. officials are making the case that Afghanistan is a model for the Western alliance to take on more security challenges around the world. But analysts argue, and U.S. officials acknowledge, that NATO has had trouble getting some members to send troops to the south of Afghanistan, where British, Dutch and Canadian forces are fighting a revived Taliban insurgency.