By deciding to abandon the 1972 Antiballistic Missile Treaty, President Bush has launched the world into a whole new uncertainty over the role of nuclear weapons.
At the height of the cold war, the ABM Treaty was an attempt to make sure these weapons were just defensive. It worked. But now as other nations try to build nuclear bombs and missiles to carry them, the United States can no longer rely on just a treaty to safeguard itself.
The treaty had to go now, because Mr. Bush wants to push ahead with the testing of a missile defense system that would violate the treaty. He tried to win support for scrapping the Soviet-era treaty from Russian President Vladimir Putin, but failed. The Kremlin, from Soviet times to the present, has held the ABM Treaty in a bear hug, as a guarantee of strategic equity with the United States. (See story, page 6.)
Russia's reaction appears to indicate it's resigned to the US move. At the moment, US-Russian relations are unusually warm. Mr. Putin and Mr. Bush hit it off personally, and Russia has been a firm ally in the war against terrorism. The two countries are moving toward agreement on a deep cut in their nuclear arsenals. The administration is betting the ABM Treaty withdrawal - hardly a surprise - won't loosen those new ties. And it's probably right. Russia has too big a stake in partnership with the US.
Perhaps more worrisome, China may react by trying to build up its small stock of missiles and warheads to maintain a credible deterrent against the US. Convincing Beijing it has nothing to fear will be a major task for Bush's diplomatic team.
Is missile defense a good investment? The president clearly has no doubts. He argues that the Sept. 11 attacks underscore a need to counter even more powerful weaponry - i.e., missiles - that may become available to terrorists. And he's right that an Al Qaeda terrorist who had such capability would try to use it.
But it's very hard to conceive how terrorists might acquire such means. And it's equally hard to conceive of "rogue nations" foolish enough to launch missiles at the US, considering what they'd get in return.
And what of the cost? The $60 billion or so needed for even a modest missile shield would put an immodest dent in the national budget in coming years.
And is there evidence the system will work? Tests so far have been ambiguous at best. But the president has recently spoken of promising results, and removing the treaty's restraints will allow more advanced testing. The technological barriers, which are high, may be surmounted. A lot will depend on whether the effort can be sustained over the long term.
That will require bipartisan support at home. Democrats generally have backed research money for missile defense, but many opposed leaving the ABM Treaty. They have deep doubts about the wisdom of massive spending on this project.
The president's announcement sets in motion a six-month notification period before the treaty actually ends. During that time, Bush will need to do more convincing with the Russians, Chinese, and, not least, the allies he'll need in Congress to move this questionable strategy forward.