None challenged the assessment by Army Lieutenant General William Wallace, the V Corps commander, but they insisted US and British forces were making "good progress" and blamed the unexpectedly stiff Iraqi resistance as the work of Iraqi "death squads" terrorizing civilians.

"I stand by this plan," said General Richard Myers, the chairman of the Joint Chiefs of Staff. "I think it's a brilliant plan."

"There are branches and sequels to everything that might happen, but the plan is sound, it is being executed and it's on track," he said.

Bush went before an audience of veterans to deliver the same message, declaring, "The current generation of our military is not letting us down. They are making great progress in the war on Iraq."

But mounting US casualties, televised images of fierce attacks on US supply lines and the surprised reaction of soldiers and officers alike to the resistance they've encountered have shattered expectations of a quick victory.

"The enemy we're fighting is different from the one we'd war-gamed against," Wallace told the Washington Post in an interview at the 101st Airborne Division headquarters in central Iraq.

Describing an opponent willing to make suicide attacks on superior US forces while using threats against fellow Iraqis to make them fight, Wallace told the Post he was "appalled by the inhumanity of it all."

"The attacks we're seeing are bizarre, technical vehicles with .50 calibers and every kind of weapon charging tanks and Bradleys," he said, referring to the M1 Abrams tanks and M2 Bradley Fighting Vehicles used by the Army.

Asked whether it now looked like the war would be much longer than planners had forecast, Wallace said, "It's beginning to look that way."

At a Pentagon press conference, US Defense Secretary Donald Rumsfeld and Myers said they had not spoken to Wallace about his remarks.

Myers highlighted the gains made in the week since the US war began, claiming that the coalition has "air supremacy" over 95 percent of Iraq and that 35 to 40 percent of the country's territory is no longer under the control of the Iraqi regime.

The leading thrust of the US invasion force is just 80 kilometersmiles) south of Baghdad, but their supply lines stretch 400 kilometersmiles) south to Kuwait along routes and through towns that have been the scene of bloody skirmishes.

Asked why it was important for US forces to get to Baghdad so quickly, Myers said, "Because we could, and it was necessary to try to bring down this regime as quickly as possible."

"I didn't say quick," he added. "I said as quickly as possible. You've heard us both stand up here and say this is going to take some time. And the tough part is yet ahead of us."

In a new complication for coalition commanders, Rumsfeld disclosed that military supplies were being shipped into Iraq from Syria and hundreds of armed Iranian-backed Iraqi militants have entered Iraq.

He warned Syria the weapons shipments were "hostile acts" that posed a threat to coalition forces, and told the Iraqi militants they would be considered combatants.

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