NATO allies wonder if the US can simultaneously defend Europe and counter any Chinese threat to Taiwan.Senior Master Sgt. Jason W. Rolfe/US Air National GuardNATO allies worry that the growing threat China poses may distract the US from Europe.A seapower expert argues the forces needed in Europe are different than in the Asia-Pacific.A confrontation over Taiwan would be primarily a naval fight; Europe would be a land battle.China's threat to Taiwan also poses a profound dilemma for NATO — does it tie up its most powerful ally from European defense at a critical moment?A new study suggests that while splitting US military resources and focus is a problem, it's a manageable one.