President Richard Nixon was (in)famous for many things; one of the most important was the "madman" strategy in foreign affairs. Presidents from FDR on tried to impress on the world their gravitas and sense of responsibility in leading a great power. Nixon, in the teeth of the Vietnam War, came up with a different strategy. "Let them think I'm crazy," he allegedly told Henry Kissinger. "Let them think I'll drop the Big One on Hanoi. Then negotiate."* Whether that played a part in the 1973 "peace" deal is another matter, but Nixon appeared to gain ever-greater enthusiasm for the strategy, until the mask began to eat the face.

The Trump administration appears to have developed, by default, a variant on the madman strategy. While the whole world is gawping at stories of decadence and chaos in the White House, US foreign policy is undergoing a shift. The Obama approach -- in which the "soft power" of trade deals, reciprocal relationships, commitment to multi-polarism, and shows of respect (and a few drones) minimising the need for direct military threat or force -- is being retrenched. In its place, there is a return to direct military presence and confrontation. Barely noticed, this represents one of the most important historical shifts of recent decades.