North Korea has now barged into the nuclear-weapons club by conducting a nuclear test. In the weeks to come, there will be much discussion about how the United States should respond. The best option is encouraging China to oust Kim Jong Il.That is not to suggest that China should invade and occupy North Korea. Rather, it should pursue more subtle subversion, and it is ideally positioned to do so, since China provides a major portion of North Korea's food and energy supplies.
The prospect of a nuclear North Korea is almost as unappealing to China as it is to the United States. The move stands to push an already aggressive Japan into remilitarizing, reasserting itself in East Asia and perhaps also building nuclear weapons.
Until now, Beijing has been reluctant to put any serious economic pressure on Pyongyang. China worries that, if it undermines Kim Jong Il's regime, the North Korean state will unravel.
Such a development could have a number of unpleasant consequences for China, including a united Korea allied to the United States, and the presence of U.S. troops on the Chinese border.
The United States can allay those fears. Washington should assure Beijing that, if China subverts Kim's government, the United States will withdraw its forces and end its alliance with South Korea. That alliance is a wasting asset. Increasingly, Seoul aligns its foreign policy with that of Beijing rather than Washington, so it is long past time for an amicable divorce.
None of the alternatives is so enticing, and some, including the military option, are positively rash. Some hawks, including Sen. John McCain (R-Ariz.), have previously suggested air strikes against North Korea's nuclear installations and missile sites. Pyongyang might well retaliate against South Korea and Japan, triggering a general war.
Proposals to impose a blockade are almost as reckless. Under international law, a blockade is an act of war, and North Korea's leaders may consider it a prelude to the real thing.
If all else fails, America should rely on deterrence and containment. As unpleasant as a nuclear North Korea might be, the United States has deterred other unsavory and volatile regimes in the past, notably Stalinist Russia and Maoist China.
Indeed, China acquired its nuclear capability on the eve of the Cultural Revolution in the 1960s. That spasm of fanaticism made China as weird a place as North Korea is today. With an arsenal of thousands of nuclear weapons and the means to deliver them with accuracy, the U.S. should be able to deter North Korea.
But the possibility of pushing Kim out without firing a shot is better. The offer of an American withdrawal from the Korean peninsula would be tempting - perhaps irresistible - to Chinese leaders, because it would make China the most influential power on the peninsula.
Chinese officials must already be pondering whether it is worth preserving the North Korean regime.
Kim ignored their warnings not to conduct new missile tests, and he has now ignored even stronger warnings that he not test a nuclear bomb.
So the Chinese may well be ready to eliminate their troublesome client - if the United States makes it worth their while. It would be a relatively painless way to end the North Korean threat for good, so we should at least explore the option.