Administration officials also assert that the acquisition of nuclear arms might embolden Mr. Hussein and increase the chances that he might use chemical or biological weapons. The officials contend that Mr. Hussein refrained from using chemical and germ weapons during the 1991 Persian Gulf war because he feared a devastating retaliatory blow from the United States and that he might now conclude that the Americans would not dare strike him if he had nuclear weapons.

''The jewel in the crown is nuclear,'' a senior administration official said. ''The closer he gets to a nuclear capability, the more credible is his threat to use chemical or biological weapons. Nuclear weapons are his hole card.''

''The question is not, why now?'' the official added, referring to a potential military campaign to oust Mr. Hussein. ''The question is why waiting is better. The closer Saddam Hussein gets to a nuclear weapon, the harder he will be to deal with.''

On the Brink of War

Hard-liners are alarmed that American intelligence underestimated the pace and scale of Iraq's nuclear program before Baghdad's defeat in the gulf war. Conscious of this lapse in the past, they argue that Washington dare not wait until analysts have found hard evidence that Mr. Hussein has acquired a nuclear weapon. The first sign of a ''smoking gun,'' they argue, may be a mushroom cloud.

Still, even though hard-liners complain that intelligence about Iraq's program is often spotty, they plan to declassify some of it to make their case in coming weeks. The administration briefed members of Congress on Iraq's programs to develop weapons of mass destruction this week, but it is not known to what extent officials talked about the intercepted shipments. Given the special intelligence-sharing relationship with Britain, the information on the attempted purchases Mr. Blair plans to release in a few weeks.

The administration's critics assert that the last decade has shown that Mr. Hussein can be contained through a combination of United Nations sanctions, carefully designed inspections and, if Iraq refused to admit the monitors, targeted air strikes. Iraq, the critics say, remains heavily dependent on external assistance to advance its nuclear program. Washington, the critics say, has time to try its hand at diplomacy and should enlist United Nations backing to force Mr. Hussein to accept inspectors back. Taken in its totality, the critics insist that the intelligence suggests there is no rush to take military action.

The Central Intelligence Agency still says it would take Iraq five to seven years to make a nuclear weapon if it must produce its own supply of highly enriched uranium for a bomb, an administration official said. American intelligence officials believe that Iraq could assemble a nuclear device in a year or somewhat less if it obtained the nuclear material for a bomb on the black market. But they say there are no signs that Iraq has acquired such a supply.