America's most famous demand that another country pull back weapons of mass destruction was delivered hand in hand with damning photographs of the weapons themselves.

This time, the evidence is not yet so black and white.

Forty years after John Kennedy stared down the Soviets on the Cuban missile crisis, President Bush is delivering goods on Saddam Hussein that have more to do with his past actions than what he might do next.

The president's speech to the United Nations last week, outlining what he called Iraq's ``decade of defiance,'' was largely about Iraqi misdeeds in the 1990s.

``If the reason for attacking Iraq has nothing to do with a future threat, if it's all about the past, then it's hard to go back to pre-emption,'' said Ivo Daalder, a foreign policy analyst for the Brookings Institution who believes the matter is diverting Bush from the anti-terror war.

So far nothing has turned up with the impact of the aerial photos of October 1962, showing Soviet missiles, launch pads and supply trailers on Cuban soil.

``Forgery,'' Soviet Deputy Foreign Minister Valerian A. Zorin snapped at a U.N. Security Council meeting. He refused to look at the pictures. But three days later, the Soviets caved.

The photos rallied domestic and international support for Kennedy's blockade of Cuba. If Bush has similar case-closing evidence to support the move toward war, he has yet to share it.

Such reluctance might be attributable to fears of revealing intelligence sources, as some Bush aides have suggested. But there's a tactical dimension as well: Challenging the international community to enforce Iraqi compliance sets up Saddam for further defiance — the tripwire for the United States to attack.

``The appeal to the United Nations was a masterstroke. It put the ball in Saddam's court,'' said Patrick Clawson, a Persian Gulf expert at the Washington Institute for Near East Policy. ``He was saying, before Sept. 11, we could live with risk; now we can't.''

Bush asserts that Iraq, by its own admission, has produced tens of thousands of liters of anthrax and other deadly biological agents for use with Scud warheads, aerial bombs and aircraft spray tanks.

He cites U.N. inspection reports that say Iraq probably maintains stockpiles of VX, mustard gas and other chemical agents, and he says it is expanding plants capable of producing chemical weapons.

And he contends Iraq would have developed a nuclear weapon by 1993 if it had not been for the Gulf War.

Bush's willingness to take the case to the international community has already paid dividends. In a sharp reversal, Saudi Arabia has suggested it would entertain being host to U.S. troops in case Iraq fails to follow U.N. orders.

Some lawmakers who heard Bush's plea Thursday for a congressional resolution authorizing ``all means ... including force'' to deal with Iraq said they detected a new moderation.

``The most important word I heard inside today from the president was the word 'if,''' said Rep. John McHugh, R-N.Y. ``He made it repeatedly clear that this resolution is not intended as a declaration of war, it is not intended as an immediate prior step to aggression.''

``The Bush administration is now facing the fact that it has to go to Congress,'' said Ellen DuBois, a University of California, Los Angeles, historian who led a petition drive this week in which dozens of historians urged Bush to consult with the legislative branch.

Iraq said this week that it is now ready to allow U.N. weapons inspectors unfettered access for the first time since 1998 — but such promises have foundered in the past once the inspectors arrived.

If that happens, Bush may go back to openly threatening pre-emptive action — and he would at least have historical precedent on his side, said Jonathan Glickstein, a U.S. historian at the University of California, Santa Barbara.

``In a sense, the arguments for the U.S. revolution were pre-emptive,'' said Glickstein, who stresses that he does not believe Bush has made a persuasive argument for pre-emptive attack. ``The taxes were seen as a harbinger of eventual enslavement.''