Bush administration officials acknowledged Friday that they had yet to compile evidence strong enough to back up publicly their claims that Iran is fomenting violence against U.S. troops in Iraq.

Administration officials have long complained that Iran was supplying Shiite Muslim militants with lethal explosives and other materiel used to kill U.S. military personnel. But despite several pledges to make the evidence public, the administration has twice postponed the release -- most recently, a briefing by military officials scheduled for last Tuesday in Baghdad.

“The truth is, quite frankly, we thought the briefing overstated, and we sent it back to get it narrowed and focused on the facts,” national security advisor Stephen J. Hadley said Friday.

The acknowledgment comes amid shifting administration messages on Iran. After several weeks of saber rattling that included a stiff warning by President Bush and the dispatch of two aircraft carrier strike groups to the Persian Gulf, near Iran, the administration has insisted in recent days that it does not want to escalate tensions or to invade Iran.


Defense Secretary Robert M. Gates seemed to concede Friday that U.S. officials can’t say for sure whether the Iranian government is involved in assisting the attacks on U.S. personnel in Iraq.

“I don’t know that we know the answer to that question,” Gates said.

Earlier this week, U.S. officials acknowledged that they were uncertain about the strength of their evidence and were reluctant to issue potentially questionable data in the wake of the intelligence failures and erroneous assessments that preceded the U.S.-led invasion of Iraq.

In particular, officials worried about a repetition of former Secretary of State Colin L. Powell’s February 2003 U.N. appearance to present the U.S. case against Iraq. In that speech, Powell cited evidence that was later discredited.


In rejecting the case compiled against Iran, senior U.S. officials, including Hadley, Gates and Secretary of State Condoleezza Rice, confirmed Friday that they were concerned about possible inaccuracies.

“I and Secretary Rice and the national security advisor want to make sure that the briefing that is provided is absolutely accurate and is dominated by facts -- serial numbers, technology and so on,” Gates told reporters at the Pentagon.

Another reason for the delay, as is often the case when releasing intelligence, was that officials were concerned about inadvertently helping adversaries identify the agents or sources that provided the intelligence, Hadley said.

Hadley also said that the administration sought to delay the release of evidence until after a key intelligence report on Iraq was unveiled, so that Americans could place the evidence in the context of the broader conflict.


That report, called a National Intelligence Estimate, was issued Friday, concluding that Iraq was deteriorating and faces a bleak future that U.S. efforts may do little to avert.

However, the report tends to downplay the role of Iran and Syria, another target of U.S. criticism, in fomenting sectarian violence, while acknowledging that Iranian involvement “intensifies” the conflict.

“The involvement of these outside actors is not likely to be a major driver of violence or the prospects for stability because of the self-sustaining character of Iraq’s internal sectarian dynamics,” says the report, compiled by experts from the nation’s 16 intelligence agencies.

Few doubt that Iran is working to increase its influence inside Iraq, but many of its beneficiaries have been political groups that also are allied with the United States.


So far, the U.S. government has provided scant evidence that the government of Iran is directly supporting militant Shiite groups.

U.S. military leaders in Iraq have said they have evidence that Iran is behind the supply network of explosives. Military officials have blamed Iran for the increasing casualties caused by the use of “shaped charge” explosive devices that can penetrate armored vehicles.

“What we are trying to do is ... counter what the Iranians are doing to our soldiers, their involvement in activities, particularly these explosively formed projectiles that are killing our troops, and we are trying to get them to stop their nuclear enrichment,” Gates said.

U.S. officials detained five Iranians in a raid in the northern Iraqi city of Irbil last month, accusing them of planning attacks on Americans.


Gates also acknowledged Friday that there was “a lot of speculation” about involvement by Iranians in the abduction and killings of five U.S. servicemen in Karbala last month. But he refused to say whether an investigation had turned up any evidence that Iranians took part.

“I would just tell you flatly that the investigation is still going on, and the information that I’ve seen is ambiguous,” Gates said. “It’s not clear yet.”

In a major speech on Iraq last month, Bush accused Iran of “providing material support for attacks on American troops” and vowed to “seek out and destroy” weapon transport networks.

Since then, Air Force officials have said they are planning new missions that could include flights along the Iran-Iraq border aimed at disrupting weapons shipments.


Iranian officials challenged the Americans to produce evidence of their charges, and Zalmay Khalilzad, the U.S. ambassador to Iraq, pledged last week to do so.

The increasingly harsh words from the Bush administration stoked fears of a possible U.S. attack on Iran. In recent days, the White House and top U.S. officials have sought to counter the concern. Gates became the latest administration official to offer such reassurances.

“The president has made clear, the secretary of State has made clear, I’ve made clear ... we are not planning for a war with Iran,” Gates said Friday.

maura.reynolds@latimes.com


Times staff writer Julian E. Barnes in Washington contributed to this report.