Washington ? The Bush administration struggled Tuesday to explain what it knows about alleged Iranian interference in Iraq after the Pentagon’s top general appeared to contradict a recently released military dossier on the subject.

At issue was a weekend briefing in Baghdad at which three senior U.S. military officials said the “highest levels” of the Iranian government had ordered the smuggling into Iraq of high-tech roadside bombs that have been killing American-led coalition soldiers.

Gen. Peter Pace, chairman of the Joint Chiefs of Staff, told reporters in the Indonesian capital, Jakarta, that U.S. forces have arrested Iranians in Iraq and some of the materials used in roadside bombs had been made in Iran.

“That does not translate that the Iranian government per se, for sure, is directly involved in doing this,” Pace said.

The assertion of Tehran’s involvement, made by U.S. officers who spoke on condition of anonymity Sunday in Baghdad, already had drawn skeptical responses from some lawmakers and other critics wary of an administration that based the invasion of Iraq on faulty intelligence.

Those doubts increased Tuesday after Pace said the link between the bomb materials and the government had not been definitively proven.

Defense experts said Pace’s comments – and the way the dossier had been presented to reporters anonymously – cast doubt on how solid the administration case is against Iran. Some suggested the apparent mixed messages were meant to keep Tehran off guard.

Michael O’Hanlon, an analyst with the Brookings Institution, a liberal-leaning think tank, called Pace’s comments “close to a contradiction” of what briefers said Sunday in Baghdad.

“Obviously, they can talk their way around it : but these guys are not naive about how words are interpreted, and the guys in Baghdad knew what impression they wanted to leave listeners with,” O’Hanlon said.

John Hutson, a retired former Navy judge advocate general and dean of the Franklin Pierce Law School, said, “I think we have to take away from it a huge dose of caution.”

“If we have disagreement within the military about the role of the Iranians, we have to proceed very cautiously,” he added.

Defense Department spokesman Bryan Whitman said Tuesday he could not explain the apparent contradiction and referred questions to Pace’s office and to American forces in Baghdad.

Asked in a CNN interview whether he believed Iranians were shipping weapons to Iraq, the top commander in the Middle East said Tuesday he didn’t know.

“I have no idea who may be actually with hands-on in this stuff, but I do know that this is not helpful to the situation in Iraq,” said Navy Adm. William Fallon.

White House spokesman Tony Snow said he had phoned Pace on Tuesday and that there was no disagreement.

“I think a lot of people are trying to whomp up a fight here that doesn’t exist,” Snow said.