http://www.msnbc.msn.com/id/16960641/site/newsweek/<snip>
U.S. officials still maintain that Iran is helping Iraqi Shia insurgents build bombs that are particularly deadly because they can penetrate armored vehicles.
But three U.S. officials familiar with unpublished intel (unnamed when discussing sensitive info) said evidence of official Tehran involvement is "ambiguous," in the words of one of the officials. For example, U.S. troops have been attacked by homemade bombs triggered by infrared sensors (like ones used on American burglar alarms). U.S. agencies know Iranian purchasers have made bulk orders for the sensors—which cost as little as $1 each—from manufacturers in the Far East.
Some analysts think most of the sensors are used for innocent purposes: they note that the devices are so widely available that would-be supporters of Iraqi militants could simply buy them in an Iranian store and smuggle them to Iraq; high-level government involvement wouldn't be necessary. (Another intel challenge: it's difficult for U.S. personnel to ID Iranian operatives among Iraqi Shiites or Iranian pilgrims who visit Shia shrines in Iraq.)
Last week U.S. military officials in Baghdad were set to brief reporters about evidence American forces had assembled about Iran's interference in Iraq.
But the briefing was canceled; one of the U.S. officials suggested it had been put off because intel officials couldn't agree about the info.