I have taught national security strategy at the Joint Special Operations University for some 15 years. Every president from Harry Truman to Donald Trump (seven Democrats, seven Republicans) has written a National Security Strategy to guide U.S. foreign policy. And while the priorities and tone changed from president to president, the substance did not. During the Cold War (1947-90), the emphasis was on containment of the Soviet Union through alliances and promoting a rules-based international system, including free trade and democratic development. The strategy was remarkably successful in Europe — not so much in the rest of the world (witness...