IT HAS BEEN three weeks since Uzbek President Islam Karimov ordered a military assault on a large crowd of opponents in the city of Andijon, killing many hundreds of men, women and children and driving hundreds of others across the nearby international border. Britain led Western governments in demanding an international investigation; after a pause, the Bush administration, which has nourished a military relationship with Uzbekistan since 2001, joined in. But Mr. Karimov, who has broken promises to liberalize one of Central Asia's most repressive regimes, has rejected outside scrutiny of the massacre. His regime continues to insist that those killed were Muslim terrorists, even though the fragmentary independent reporting from the city strongly suggests that most of the victims were ordinary citizens fed up with Mr. Karimov's repression. His intransigence creates an urgent question for the Bush administration: whether it can continue a security alliance with a dictator who has just used his army to slaughter hundreds of his own citizens.

The answer would seem to be fairly easy for a president who has repeatedly committed himself to promoting freedom in the Muslim world and repudiated the past U.S. practice of allying itself with repressive dictators in exchange for security cooperation. Mr. Karimov, a member of the Soviet Union's last Politburo, is a classic example of this sort of tyrant. Facing a real if limited threat from Islamic militants, he has responded by indiscriminately repressing Muslim activists across his country; the trouble in Andijon started with the prosecution of nearly two dozen prominent businessmen. Thousands of political prisoners suffer in prisons; many have been tortured, and at least one was boiled to death. Apart from the questionable morality of supporting such a regime, the United States risks contaminating its long-term interests in Uzbekistan. Sooner or later Mr. Karimov's policies will lead to his downfall, and if they are like other subject peoples, Uzbeks will not soon forget who supported the dictatorship.

This logic and the president's announced policy appear to have had little impact on the Pentagon, which jealously guards its relationship with Mr. Karimov and has deliberately undercut past attempts by Congress and the State Department to pressure him. The Defense Department continues to negotiate for long-term access to a military base in southeastern Uzbekistan that it has used since the intervention in Afghanistan -- even though U.S. troops and aircraft are now stationed at large bases in Afghanistan itself. Defense Department statements on Uzbekistan remain strikingly out of sync with those of the State Department, the White House and leading Republicans in Congress. "When you look at the totality of what Uzbekistan has been doing, they've been a very valuable partner and ally in the global war on terror," spokesman Bryan Whitman said to The Post last week. "Clearly, our continued engagement we feel is pretty important."

Other administration officials say a review is underway about the U.S.-Uzbek relationship, including the continued use of the Karshi Khanabad base. Three Republican senators who visited Tashkent last week -- John McCain, Lindsey O. Graham and John E. Sununu -- have rightly called for the security relationship to be reconsidered. Democratic Sen. Patrick J. Leahy has appropriately asked for an investigation of whether U.S.-trained units were among those participating in the massacre. Uzbekistan is a test of whether President Bush intends to implement the democracy doctrine he has proclaimed for the past two years -- and whether he will continue to allow the Pentagon to pursue an entirely contrary policy.