It’s difficult to understand the foreign and national security policy of U.S. President Donald Trump. While there are consistent themes and patterns, Trump’s approach to the world seems bereft of an overarching logic. It is the first American strategy for decades not shaped by a discernible vision for world order.

As Hastings Ismay, NATO’s first secretary-general, put it, the alliance’s purpose in Europe was to keep the Russians out, the Americans in and the Germans down. By all indications, U.S. President Donald Trump, in Brussels for his second NATO summit, is dead set on reversing all three elements of Ismay’s formula.