Japan is in crisis. It has been hit by the worst earthquake it's experienced--8.9 on the Richter scale-- since the 1923 Tokyo one that caused immense damage and is well-described by Joshua Hammer in a vivid book. Hammer argued that the earthquake unleashed nationalist impulses that led to roving bands attacking Koreans living in Japan and, ultimately, paved the way for World War II.

There's little chance of that happening today. Japan has fundamentally changed from the militaristic society of the pre-war, though a strong nationalist element remains active. But President Obama should send whatever aid Japan needs and underscore that it is a vital American ally. Obama has already announced that America "stands ready to help." Tsunami warnings have also been issued for California, Oregon, and Hawaii.

The earthquake offers a reminder that natural disasters constitute their own kind of crisis. The earthquake could prompt Japan to regroup and recover from its decades-long slump--or it could prove the body blow that ends any remaining aspirations to be a major power. It's in America's moral and strategic interest for it to remain one. China should assist Japan as well.

At a moment when Paul Wolfowitz is demanding that America intervene in Libya in today's Wall Street Journal, it is appropriate to wonder just how much Obama is supposed to take on. Libya will probably end up looking like a sideshow. But in Washington, reality does not always prevail: Obama's Director of National Intelligence, James Clapper, was drubbed for announcing that Russia and China are America's main threats and that Col. Ghadaffi, the mad dog of the Middle East, as Ronald Reagan once put it, will likely prevail over the rebels. Washington is a place where you can get punished for telling the truth.

But perhaps this new disaster will, at least temporarily, inject some sobriety into debates about American foreign policy. Obama would do well to avoid distractions. A vital ally is suffering. Our principal obligation is to help it.