Crowley and other critics of the Bush administration say that's where planning for the occupation of Iraq has failed. War planners didn't send enough U.S. troops and failed to win enough support from other countries.

"We did the war without completely understanding how to do the peace," Crowley said. "We're ad hocing the peace."

More U.S. servicemen have died in Iraq since the end of major combat operations was declared May 1 than during the six-week invasion. Terrorist car bombings have ripped through the United Nations' Baghdad headquarters and other civilian targets.

A recent survey by the military newspaper Stars and Stripes found many troops in Iraq expressing sentiments similar to their Beirut counterparts. Roughly a third said their morale was low and their mission ill-defined. They characterized the war in Iraq as having little value.

But Armitage, the deputy secretary of state, said there are key differences between the mistakes in Lebanon and Iraq today.

"In Lebanon, we didn't have a clear mission," he said. "We didn't understand the complexities."

In Iraq, he said, the troops have that clear mission — creating stability. Two-thirds of servicemen agreed in the Stars and Stripes poll. And other policymakers argue that troops need to stay until that mission is accomplished.

"There would be lingering perceptions of Beirut today if we pulled out of Iraq prematurely," said Dennis Ross, a Middle East envoy under two presidents. "The perception would be the U.S. intervenes, but it does not stay."