"That will generate a constitutional confrontation in the Senate, I predict to you," Sen. Joseph Biden, D- Del., told Secretary of State Condoleezza Rice Thursday.
U.S. President George W. Bush made repeated references to Iran's involvement in Iraq and threat to regional stability in his Wednesday night speech.
Chairman of the Joint Chiefs of Staff Gen. Peter Pace told reporters Thursday morning the military has not recommended conducting operations inside Iran. It is confining its operations against Iranian agents to those already inside Iraq.
"What we've been doing and we'll continue to do is to track the networks of individuals regardless of their nationality inside of Iraq that are providing weapons that are designed to kill our troops," Pace said. "I think it's instructive that in the last couple of weeks two of those raids that we conduct to go after these folks that are providing these kinds of weapons, two of those raids had policed Iranians. So it is clear that the Iranians are complicit in providing weapons, and it's also clear that we will all we need to do to defend our troops in Iraq by going after the entire network regardless of where those people come from.
"We can take care of the security for our troops by doing the business we need to do inside of Iraq, and there are other (diplomatic) methods ... to deal with government-to-government relationships with Iran. But with regard to those who are physically present trying to do harm to our troops, regardless of nationality, we will go after them and defend ourselves," Pace said.
Also Thursday, U.S. troops reportedly raided Iranian government offices in northern Iraq.