There can be no doubt that China’s success in shooting down one of its aging weather satellites in orbit is a serious matter. The question now is what to do about it.

Details of the Jan. 11 missile shot are still unclear. China waited nearly two weeks to confirm it and has offered no explanation of how or why except to say that China “never has and never will participate in any form of arms race in space.” Speculation as to China’s motive has ranged from demonstrating its strength and importance to the world, preparing for any possible encounter with Taiwan, and impressing its own military leaders. China said in a defense white paper in December that its strategic goal is to build a military “capable of winning informationized wars by the mid-21st century.”

Bruce Berkowitz, a research fellow at the Hoover Institution at Stanford, suggests that a “killer satellite” may have been the weapon used by China. In an article in The Wall Street Journal, he says that a killer satellite can destroy another satellite by ramming it or shooting it with a mass of pellets. In either case, the result is a huge amount of debris in orbit.

Banning killer satellites is impossible without banning all satellites, he writes, since they use the same technology. But he makes a persuasive case that the United States and China have a mutual interest in limiting space debris and could agree to cooperate: “We’ll never demilitarize space. But we can make it a safer place to work.”

So the weaponization of space is already here. And both war and economic development are increasingly dependent on the swarm of satellites circling the earth and now shown to be vulnerable. And the destruction of the Chinese satellite has added to the 11,000 sizable bits of space trash racing through space at 3,000 miles an hour that already threaten the commercial, communication and military satellites. It is no secret that the chief motivation of the U.S. development of space exploration and technology is their military applications. The same goes for other nations.

Another genie is out of the bottle. This new threat comes after a whole cluster of nations either have entered the nuclear club or are on the way to doing so. In some cases, like Israel, Pakistan and India, the Bush administration accepts or even encourages their nuclear programs. In the case of Iran and North Korea, the administration relies on hints of military strikes, economic pressure, and hopes of regime change.

Those moves haven’t worked with Iran and North Korea, and they would have even worse prospects against China, which is far too big to be pushed around.

A seemingly obvious solution could be an international treaty.

That may be the best we can hope for as the nuclear age takes one more hazardous step forward.