From the AP...

WASHINGTON -        President Bush has authorized U.S. forces in        Iraq to take whatever actions are necessary to counter Iranian agents deemed a threat to American troops or the public at large, the White House said Friday.
 
"It makes sense that if somebody's trying to harm our troops, or stop us from achieving our goal, or killing innocent citizens in Iraq, that we will stop them," Bush said. "It's an obligation we all have ... to protect our folks and achieve our goal."

The aggressive new policy came in response to intelligence that        Iran is supporting terrorists inside Iraq and is providing bombs _ known as improvised explosive devices _ and other equipment to anti-U.S. insurgents.

Full story here:  http://news.yahoo.com/s/ap/20070126/ap_on_go_pr_wh/us_iran

??? And they'll be able to tell the Iranian agents apart from the terrorists how?