A miscalculation this time could lead to some kind of renewed military action by the United States-probably airstrikes at one or more Iraqi nuclear sites that had not been bombed during the war. That, at least, was what a number of well-placed sources within the Bush administration seemed to be signaling last week. While it was still entirely possible that the incipient crisis could be resolved by negotiation, no one in Washington could be sure that Saddam Hussein would take the cue and back down. At issue was Iraq’s compliance with the terms of the April cease-fire agreement with the U.N. Security Council, and particularly with those sections that allow U.N. inspectors to monitor the dismantling of Iraq’s weapons of mass destruction-chemical weapons, missiles and nukes. An incident on June 28, when Iraqi troops fired warning shots over the heads of U.N. inspectors who were trying to check on a mysterious Iraqi Army convoy near Bagdad, has now led U.S. and U.N. officials to assume the worst. The trucks, hastily loaded and even more hastily driven away from the Army base at Falluja, seemed to be carrying equipment used to make fissionable material for atomic bombs.

While no one thought the Iraqis were yet able to assemble a deliverable nuclear weapon, U.S. intelligence agencies were convinced that Saddam Hussein was concealing as many as 20 electromagnetic isotope separators, or calutrons, that are used to make plutonium from enriched uranium. In fact, NEWSWEEK has learned, the U.N. team’s photographs of the fleeing Iraqi convey clearly showed disc-shaped machine components that fit the description of a calutron’s innards. Such equipment would, of course, pose the long-term possibility of a revived Iraqi military threat in the Persian Gulf region, and it would be a clear attempt to flout the authority of the United Nations.

Last week, according to NEWSWEEK’S sources, the Security Council informally agreed that Iraq had failed to comply with the U.N. mandates. “There was a consensus that Iraq has been hiding something, and that that ‘something’ is a nuclear-weapons program based on enriched uranium,” a U.S. official said. The Security Council also agreed that a letter from Saddam Hussein, in which the Iraqi leader promised to provide a list of the equipment sought by the U.N. inspectors, would not be accepted as compliance. Abdul Amir al-Anbari, Iraq’s U.N. ambassador, was called to a closed-door session with the five permanent members of the Security Council and responded with what a U.S. source described as “the usual dissembling.” “You have a problem,” said Soviet U.N. Ambassador Yuli Vorontsov.

The game plan now, according to U.S. officials, was to give Saddam Hussein one last chance to prove his good intentions. On Saturday, a 37-man U.N. inspection team left Bahrain for Baghdad, and Iraqi officials promised to provide the list of suspect equipment by Monday morning. But, said an informed U.S. official, “we don’t want to see lists. We want to see the equipment that was taken away, and we want to destroy it. Don’t tell us that you’ve destroyed the items.” As a result, this official said, the U.N. team’s real mission would be to mount a “challenge inspection” of the suspected calutrons or a nuclear-related site recently identified by U.S. intelligence. (The intelligence data, NEWSWEEK sources have said, initially came from an Iraqi defector who claimed that U.S. forces failed to find at least four nuclear-weapon sites during Desert Storm. Worse, the defector said, the Iraqis had secretly accumulated 88 pounds of weapons-grade material-enough for two Nagasaki-type atomic bombs-before the war began. That material, presumably a matter of serious concern for U.S. and U.N. officials, has not been found.)

Bush bluntly accused Saddam Hussein of “cheating and lying” and warned the Iraqis to provide “total, free, open inspections” for the U.N. team. And that, at the weekend, was where things stood: according to administration sources, the president was ready to approve U.S. airstrikes against Iraq if the U.N. inspection team was blocked or obstructed by Iraqi officials. The approximate timing of such a raid was, of course, not discussed by anyone in Washington and would depend on further consultation with the allies. But, NEWSWEEK sources indicated that military action might well begin before the G-7 economic summit in London next week if Saddam Hussein proved obdurate. Once again, the United States and its allies were trying to send a stern message to Baghdad-and once again, no one knew whether Saddam Hussein would blink.