WASHINGTON -- In February 1946, George Kennan, then a political officer in the U.S. Embassy in Moscow, sent an 8,000-word telegram to the State Department, warning about Soviet behavior. A little over a year later, a version of that telegram appeared in Foreign Affairs magazine, written by "Mr. X."

That article became one of the pillars of the U.S. policy of containment of the Soviet Union. Later, Kennan would regret that his message was misread and commandeered by hardliners: He bemoaned the reliance on the military dimension of the conflict with the Soviet Union, arguing that the real challenge was political.

I fear we are approaching a Mr. X moment with China. In the last year, the tone of U.S. relations with China has changed dramatically. A year ago, then-U.S. Secretary of State Colin Powell could call the U.S.-China relationship "the best ever." No official in Washington or Beijing would say that today with a straight face.