The defense budget of the United States, the world's leading military power throughout the twentieth century, is not enough for the country to confront the threats of the twenty-first. It should be increased -- and can be without negatively affecting the economy. The money is available; it must be joined by political will.

Margaret MacMillan's engaging narrative history shows how Nixon's trip to visit Mao helped end the Cold War. But neither leader anticipated how fast China would rise or how that rise would force the U.S.-Chinese relationship to evolve.

The White House still avoids the label, but by any reasonable historical standard, the Iraqi civil war has begun. The record of past such wars suggests that Washington cannot stop this one -- and that Iraqis will be able to reach a power-sharing deal only after much more fighting, if then. The United States can help bring about a settlement eventually by balancing Iraqi factions from afar, but there is little it can do to avert bloodshed now.