The top commander of U.S. Marines (search) in Iraq said Friday he is surprised that extensive searches have failed so far to discover any of the chemical weapons that American intelligence had indicated were supplied to front line Iraqi forces at the outset of the war.

Lt. Gen. James Conway, commander of the 1st Marine Expeditionary Force, said in a video teleconference from his headquarters in southern Iraq that he was convinced before and during the war that at least some Republican Guard units had been provided with chemical weapons.

"It was a surprise to me then -- it remains a surprise to me now -- that we have not uncovered weapons, as you say, in some of the forward dispersal sites," he told reporters at the Pentagon.

"Believe me, it's not for lack of trying," he added. "We've been to virtually every ammunition supply point between the Kuwaiti border and Baghdad, but they're simply not there."

Conway added that it was too soon to say whether this amounted to a U.S. intelligence failure or whether it meant that the Bush administration had been wrong about Iraq's weapons programs.

The administration's main justification for attacking Iraq was the assertion -- yet to be validated -- that Iraq possessed chemical, biological or other weapons of mass destruction and that it was actively pursuing a nuclear weapons capability.

"What the regime was intending to do in terms of its use of the weapons, we thought we understood, or we certainly had our best guess, our most dangerous or most likely courses of action that the intelligence folks were giving us," Conway said. "We were simply wrong."

"Whether or not we're wrong at the national level I think still very much remains to be seen," he added.

Conway said it remained possible that if those who are continuing the search for weapons of mass destruction in Iraq manage to "ask the right question of the right person," then they may be led to hidden weapons.

Some in Congress are openly questioning the administration's insistence that it may take a long time to find any such weapons. Sen. Jay Rockefeller of West Virginia (search) the top Democrat on the Senate Intelligence Committee, said in an interview Thursday the logic of the administration's position -- that the weapons were well hidden -- does not hold up.

"You can't quite say that it's going to take a lot more time if the intelligence community seemed to be in general agreement that WMD was out there," Rockefeller said. If the weapons were so well concealed, the United States should have considered giving U.N. inspectors more time to find them, he added.

It has been the contention of Defense Secretary Donald H. Rumsfeld (search) and other senior administration officials that no one should be surprised that no Iraqi weapons have been found yet. Rumsfeld on Thursday reiterated his argument that because Iraq had become so good at deceiving U.N. weapons inspectors, it should not be surprising that no weapons have been found yet.

Conway, the three-star general whose Marines are now occupying the portion of southern Iraq between Basra and Baghdad, also said his troops are not encountering the kind of violence and renegade resistance that Army soldiers are facing in Baghdad and other parts of the country.

He said this may be largely because southern Iraq has more Shiite Muslims who are happy to have been liberated from a Saddam Hussein regime that repressed the Shiite population. There also are fewer members of the former ruling Baath Party in the south, he said.

The Marines' reception by Iraqis has been "overwhelmingly positive," he said.

Nevertheless, there has been some anti-American resistance, and the Marines have attempted to deal with by acting pre-emptively, Conway said. He cited as an example an attack his forces made Thursday on five locations where former Baathists apparently were training for future attacks against Americans.

The Marines found rocket-propelled grenades and automatic weapons and detained 13 people, one of whom was identified as a "fairly high-level" Baathist, Conway said. Two Iraqis were shot in the attack, he said.

Conway said there are about 41,000 Marines in Iraq and that the timing of their return home will depend in part on the United States' success in persuading more countries to provide peacekeeping forces in Iraq.