Our current military focus is on the two ongoing wars: Iraq and Afghanistan. But neither of these poses an existential threat to the United States.

We do have an enormous concern with China. However, our focus is on domestic economic issues. It is only a question of time until China surpasses the United States as the world's largest economy. Chinese universities are graduating five times as many engineers as the United States. They are now our bankers, holding the treasury bonds and notes that keep the United States afloat.

Last month, I was having dinner in Washington with a couple who had just returned from their first trip to China. They spoke about what they saw: The enormous building; the overnight development of huge factories and mega cities; and the incessant energy. I imagined that similar conversations took place a hundred or so years ago in London when a couple returned from a visit to the United States.

It would be convenient to view China's competition with the United States in purely economic terms. But that would be naive and foolish. We can no longer close our eyes to the growing Chinese military and to the risk that the United States and China could be drawn into a large scale war with horrendous consequences for both nations.

The spring issue of Foreign Affairs had on its cover: "Will China's Rise Lead to War?" And I know from a source in the Pentagon that a special unit is dedicated to carefully monitoring China's military expansion, while at the same time playing war games that pit the United States against China.

Recent developments underscore this looming threat. In January of this year, then Defense Secretary Robert Gates visited China with the objective of improving defense ties. While he was there, with a bold, in your face, show of strength, China's military conducted a test flight of a new stealth fighter jet.

Then on June 4, Gates threw down the gauntlet to China in a speech before a group including the Chinese Defense Minister. Gates declared that the United States was developing a new air-sea battle strategy "in defense of our allies and vital interests in Asia."

There are a multitude of potential flashpoints for war between the United States and China.

One is Taiwan. Beijing regards Taiwan as a renegade Chinese province, not an independent nation. And the United States has treaty commitments to defend Taiwan. A second potential flashpoint is oil. For both the United States and China, these limited resources are the lifeblood of their economies.

A third potential flashpoint is Japan. The Chinese still have a score to settle with Japan for World War II, and there are plenty of issues between those two nations, including fishing and navigation rights. On the other hand, the United States has treaty obligations to Japan.

In these and in other scenarios, war between the United States and China is not inevitable. However, it's time we began confronting the risk of this occurring. We must be prepared. We cannot afford to say we never saw it coming.