Bush, at a news conference, also said he would fight any attempt by the Democratic-controlled Congress to cut off money for the war. "They need to fund our troops and the need to make sure we have the flexibility necessary to get the job done," he said.

The House is expected to vote Friday on a nonbinding resolution opposing Bush's decision to send 21,500 additional troops to Iraq.

The meeting with reporters in the East Room was Bush's first news conference since Dec. 20 and the first since he announced the troop buildup in Iraq. The four-year-old war hangs heavily on his presidency, and Bush's approval rating in an Associated Press-Ipsos poll in February matched an all-time low of 32 percent.

Iran was a dominant theme of reporters' questions because of conflicting statements about U.S. intelligence in Iran and recurring speculation that Bush is looking for an excuse to attack the Islamic republic, which is believed by Washington and its allies to be seeking nuclear weapons.

Defending U.S. intelligence that has pinpointed Iran as a hostile arms supplier in Iraq, Bush said, "Does this mean you're trying to have a pretext for war? No. It means I'm trying to protect our troops."

There have been mixed signals in the administration about Iran's involvement in supplying Shiite groups in Iraq with a particularly lethal type of roadside bombs known as explosively formed penetrators.

Three senior U.S. military officials, at a weekend briefing in Baghdad, said the highest levels of the Iranian government had ordered the weapons smuggled into Iraq. They based their claim on the belief the weapons are moving into Iraq through the Iran's Revolutionary Guards elite Quds Force.

But Gen. Peter Pace, chairman of the Joint Chiefs of Staff, said later he was not ready to conclude that Iran's top leaders were behind the attacks. Some lawmakers also have questioned the administration's statements.

Wading into the debate, Bush said the Quds Force was instrumental in supplying the weapons ¡ª "we know that," he said ¡ª and that the Quds Force was part of the Iranian government. "That's a known," he said. "What we don't know is whether or not the head leaders of Iran ordered the Quds Force to do what they did."

Pressed again on the subject, Bush displayed some irritation and said, "Whether (Iranian President Mahmoud) Ahmadinejad ordered the Quds Force to do this, I don't think we know. But we do know that they're there and I intend to do something about it. And I've asked our commanders to do something about it. And we're going to protect our troops." Ahmadinejad has denied Iran was behind the attacks.

Democrats on the Senate Armed Services Committee emerged from a classified briefing Wednesday saying they wanted more information about Iran. The committee chairman, Sen. Carl Levin said it was unclear to him precisely what the administration knows about the Tehran government's ties to the weapons found in Iraq.

"There seems to be some disarray," said Levin, D-Mich. He said he eventually hopes to see some declassified information on the subject.

Bush came into the news conference after receiving a briefing from Baghdad by Gen. David Petraeus, the new commander of U.S. forces in Iraq.

Bush said he talked with Petraeus about coordination between Iraqi and coalition forces, and that while it seemed to be good, more work was needed on developing an efficient command-and-control structure.

Bush responded carefully when asked about Russian President Vladimir Putin's accusations Saturday that the United States was undermining global security and provoking a nuclear arms race. The depth of Putin's criticism surprised U.S. officials.

Bush said Putin was "the same strong-willed person" he has known since 2001 and there is a "complicated relationship" between Washington and Moscow.

On other matters, Bush said:

_The agreement announced Tuesday to shut down North Korea's nuclear program in exchange for fuel assistance was "a good first step." He said he strongly disagreed with former U.N. Ambassador John Bolton that it was a bad deal.

_He will not comment on the 2008 presidential race. "I will resist all temptation to become the pundit-in-chief."

_He will not comment on whether he authorized members of his administration to leak the identity of Valerie Plame, a one-time CIA officer whose husband, former ambassador Joseph Wilson, criticized the administration's case for the Iraq war. Similarly, Bush refused to say whether he might pardon I. Lewis "Scooter Libby, the former aide to Vice President Dick Cheney. Libby is on trial on charges of lying and obstructing the investigation into the Plame's identity.