"In the years gone by, NATO summits were important events in the life of the alliance. Over the past two decades, however, the gatherings became almost annual, and therefore less than exciting. Until the 2017 NATO summit in Brussels, that is. Trump livened things up by not referring to the North Atlantic Treaty's iconic article 5, which stated that "an armed attack against one or more of them in Europe or North America shall be considered an attack against them all." This provision is actually less binding than its reputation, since each alliance member will merely take "such action as it deems necessary." It had been invoked only once, after the 9/11 attacks on New York and Washington. Nonetheless, NATO had been a successful deterrence structure, for decades blocking the Red Army from knifing through Germany's Fulda Gap and deep into the heart of Western Europe. Of course, the United States was always the overwhelmingly greatest force contributing to our alliance, and it was primarily for our benefit, not because we were renting ourselves out to defend Europe, but because defending "the West" was in America's strategic interest. As a Cold War bulwark against Soviet expansionism, NATO represented history's most successful politico-military coalition."