WASHINGTON — American forces in Iraq yesterday wasted no time in implementing President Bush’s new gloves-off policy toward Iran, raiding an Iranian building in northern Iraq and arresting five Iranian Revolutionary Guard operatives.

The raid caused diplomatic tremors in Tehran and Kurdish Iraq just as the new policy opened a new divide between the White House and leading Democrats, prompting the new chairman of the Senate Foreign Relations Committee to declare that any

military actions in Iranian territory would require explicit authorization from Congress.

An American intelligence official yesterday, speaking on condition of anonymity, described the five Iranians and another individual picked up in the raid in Irbil as “high value terrorists.” This official said that the individuals were believed to be behind attacks on American soldiers and random Iraqis. He said details would become clearer as American military intelligence officers finished combing through the office’s hard drives and documents and as the suspects underwent interrogation. Another administration source yesterday said the White House and State Department do not consider the Iranians arrested yesterday to have diplomatic immunity because the building that was raided was not a consulate. This means that unlike senior Iranian officials arrested last month, those detained yesterday will likely not be returned to Iran.

The arrests came as the toll the war is taking on America was visible in a dramatic White House event in which President Bush shed a tear while meeting with the family of a Marine from New York, Jason Dunham. Dunham was posthumously awarded the Medal of Honor after covering a grenade in Iraq to protect his fellow leathernecks.

In Tehran, the Iranian foreign ministry summoned for censure both the Iraqi ambassador and the Swiss ambassador who represents American interests. Meanwhile the Kurdistan Regional Government also publicly protested the raid on what they said was an Iranian consulate. ABC News last night reported that American soldiers tried but failed to arrest more Iranians at the Irbil Airport but were thwarted by Kurdish Peshmerga sources.

The arrests yesterday appear to be part of a new American policy towards Iran unveiled last night by President Bush in his new war strategy. In that speech the president promised that Americans would disrupt supply lines to Iraq from Syria and Iran and “seek out and destroy the networks providing advanced weaponry and training to our enemies in Iraq.”

This passage of the speech has troubled the chairman of the Senate Foreign Relations Committee, Senator Biden, a Democrat from Delaware. Yesterday at hearings on the new strategy, he asked Secretary of State Rice if the president believed he had the constitutional authority to conduct cross border raids from Iraq into Iran or Syria. Ms. Rice yesterday said in response, “I would not like to speculate on the president’s constitutional authority or to try and say anything that certainly would abridge his constitutional authority, which is broad as commander in chief.”

In response to an earlier question about whether the new policy meant that such raids were now authorized, Ms. Rice referred Mr. Biden to remarks from the chairman of the joint chiefs of staff, General Peter Pace. In those remarks he ruled out for now the prospect of cross-border activity. “We can take care of the security for our troops by doing the business we need to do inside of Iraq,” he told reporters outside of another hearing.

Mr. Biden, however, was not satisfied. He sent a letter yesterday afternoon to the White House asking the president whether he believed he had the authority to authorize such raids. At the hearing yesterday, he said, “I just want to make it clear, speaking for myself, that if the president concluded he had to invade Iran or Iraq in pursuit of these — or Syria — in pursuit of these networks, I believe the present authorization granted the president to use force in Iraq does not cover that, and he does need congressional authority.”

The Justice Department lawyer who helped draft many of the legal authorities after September 11 used by the White House to justify intensive interrogations, John Yoo, yesterday said he did not agree with Mr. Biden’s reading of the Constitution with regard to hot pursuit. “As a matter of practice and history, presidents have used force abroad without any congressional authorization,” Mr. Yoo said in an e-mail to The New York Sun, “including the war in Kosovo, which I do not recall Senator Biden challenging as a violation of the Constitution.”