Some details on yesterday's U.S. military EFP show and tell in Baghdad.
But while the find gave experts much more information on the makings of the E.F.P.'s, which the American military has repeatedly argued must originate in Iran, the cache also included items that appeared to cloud the issue.
Among the confusing elements were cardboard boxes of the gray plastic PVC tubes used to make the canisters. The boxes appeared to contain shipments of tubes directly from factories in the Middle East, none of them in Iran. One box said in English that the tubes inside had been made in the United Arab Emirates and another said, in Arabic, "plastic made in Haditha," a restive Sunni town on the Euphrates River in Iraq.
The box marked U.A.E. provided a phone number for the manufacturer there. A call to that number late Monday encountered only an answering machine that said, "Leave your number and we will call you back."
Anthony H. Cordesman, who holds the Arleigh A. Burke chair in strategy at the Center for Strategic and International Studies in Washington, said that despite those confusing new elements, the United States has been cautious in how it has presented the possible evidence of Iranian involvement.
"The case that has been made has been very careful and very restrained," Mr. Cordesman said. "If this is unrealistic, it can't be blamed on the intelligence community. This has had the highest possible policy level review, and credibility on an international level is clearly the major criteria in reviewing everything that was said."
Other analysts have expressed skepticism that the American military has made a strong case for the Iranian origin of the E.F.P.'s as tensions are running high between the United States and Iran over its nuclear program.
Items in the cache included the concave copper dishes called liners that cap the canisters and roll into deadly armor-piercing slugs when the explosive detonates. There were also various kinds of electronics, presumably for arming and triggering the devices, the PVC tubes, and two types of rockets and mortar shells that Major Weber said had markings and construction that identified them as being Iranian in origin.
The PVC tubes, of several different sizes, appeared to be fittings of the kind of used to splice two stretches of PVC tube together in routine applications.