BAGHDAD, Iraq -- U.S. defense and intelligence officials, seeking to lend credibility to allegations that Iran is providing weapons to Shiite militants in Iraq, displayed munitions and fragments of weapons yesterday that they said constituted solid evidence that Tehran was contributing to Iraq's violence.
They also alleged that a group under the command of Iran's supreme leader was behind the smuggling of the weaponry across the Iran-Iraq border.
The briefing, held under unusually secretive circumstances, featured three U.S. officials, none of whom would be identified by name, and two tables laden with what they said were uniquely Iranian military hardware and weapons fragments.
The U.S. officers claimed that Iranian weapons known as explosively formed penetrators have been responsible for the deaths of about 170 of the 3,400 American-led forces killed in Iraq. The devices are used in armor-piercing roadside bomb attacks that have increased over the past year, the military said.
The officers presented fairly strong evidence that the weapons and components were manufactured in Iran; the claims that Iranian officials had orchestrated their smuggling into Iraq and that the weapons were primarily intended for use against U.S. and Iraqi forces appeared weaker.
Experts wondered whether it was possible to discern the intended uses of such weapons in a situation as complex as Iraq's.
"There is a virtual civil war happening," said Wayne White, a former State Department intelligence analyst who is now a scholar at the Middle East Institute, a Washington think tank. "If Iran is passing munitions to Shia militias, it could be more in the context of the ongoing sectarian strife than aimed at the U.S."
The presentation came as tensions continue to mount between Washington and Tehran over Iran's nuclear ambitions and regional aspirations. With two U.S. warship groups moored or near position off Iran's Persian Gulf coast, the allegations immediately raised suspicions among critics that the Bush administration was trying to build a case for war against Iran the same way it used intelligence to win support for the U.S. invasion of Iraq.
"That's how we got into the mess in Iraq," Sen. Christopher J. Dodd, a Connecticut Democrat, said on CBS television. "That's why some of us supported those resolutions, because of doctored information. So I'm very skeptical based on recent past history about this administration leading us in that direction. It worries me."
But the presentation also seemed deliberately limited in its scope. The U.S. officers appeared to back away from long-standing claims that Shiite Iran was supporting the Sunni insurgents in western Iraq and others parts of the country who have killed the largest number of U.S. troops. Instead the officers alleged that Shiite groups ostensibly loyal to radical anti-American Shiite cleric Muqtada al-Sadr were involved in the smuggling and use of the weapons.
The U.S. officers said the presentation was an attempt to fend off an alarming new type of weaponry that was hurting a growing number of American and Iraqi troops.
Many also saw the presentation, which was scaled back because of concerns in Washington, as a defensive maneuver, meant to drive a wedge into the increasingly cozy relationship between the Shiite-led governments in Baghdad and Tehran as a new U.S.-backed Baghdad security plan gets under way.
"The Iraqi government doesn't think Iran is the enemy," said Mahmoud Othman, an Iraqi Kurdish lawmaker. "The Americans are trying to convince the Iraqis that they're not just against Iranians because of the nuclear file, but because of what's happening here in Iraq."
Several Iranian officials contacted by phone in Tehran yesterday evening declined to comment on the presentation
Few independent analysts believe that Iran or any other foreign country plays a decisive role in the sectarian warfare, insurgent violence and banditry engulfing at least eight of Iraq's 18 provinces. But western intelligence and Middle East experts mostly believe that the intensely secretive government in Tehran is pursuing a policy of "managed chaos" in Iraq to achieve its strategic objectives. They suggest Iran is supporting its ascendant Shiite and Kurdish allies dominating the new government while simultaneously contributing to violence in an effort to keep the U.S. preoccupied and constrained.
U.S. officials said the material presented yesterday to about three dozen Iraqi and Western journalists was just a portion of what exists, but that Americans were limited in what they could show because of concerns that advertising the deadliness of the weapons might encourage militants to step up attacks.
The briefing had originally been scheduled nearly two weeks ago but was postponed because of conflicting opinions between different political factions within the Bush administration over the quality of the evidence.
Yesterday's presentation could be seen as a general warning to Iran, part of an aggressive policy of containment meant to curtail Iran's ambitions in Iraq and beyond.
"It's part of the deterrence game," said Ken Wise, an analyst at the Dubai Consultancy Research and Media Centre, a United Arab Emirates think tank.
Tina Susman and Borzou Daragahi write for the Los Angeles Times.