When Defense Secretary Robert Gates devoted his final policy speech this month to berating NATO and our European allies, he was engaging in a time-honored tradition: Americans have worried about Europeans shirking their share of global burdens since the start of the 60-year-old alliance. Gates sounded a pessimistic note, warning of “the real possibility for a dim if not dismal future for the transatlantic alliance.” Yet, the outgoing Pentagon chief may not have been pessimistic enough.