NATO was designed to ensure quick American involvement and wide European influence over our action, but the strain of demanding problems outside of Europe and too little muscle from Europeans in solving them have taken a serious toll. The U.S. military is no longer NATO-centric, preferring to fold allies into operations individually in regional military headquarters than involve the machinery of politico-military decision-making in NATO.
Whether or not the current intertwining of defense establishments in NATO continues, the United States would surely come to a NATO ally’s assistance if it were attacked. But the response may parallel more closely U.S. assistance in World War I and II, with an extended duration where the American public and Congress resist involvement. NATO’s nuclear guarantee will be substantially less credible if, as several allies have proposed, shared responsibility for nuclear missions is ended.