US Secretary of State Condoleezza Rice, center, is saluted by the US embassy staff as Zalmay Khalilzad, right, the US ambassador to Iraq, walks alongside her in Baghdad, Iraq, Saturday, Feb. 17, 2007. [AP]

BAGHDAD, Iraq - US Secretary of State Condoleezza Rice told Iraqi government leaders Saturday that the contentious debate in Washington over President Bush's war strategy reflects US doubts that democracy will prevail over violence.

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"Some of the debate in Washington is in fact indicative of the concerns that some of the American people have ... if the Iraqi government doesn't do what it has said it will do," Rice said she told leaders from all of Iraq's factions.

Rice made an unannounced visit to Baghdad as the US Senate deadlocked on whether to repeat a symbolic rebuke that the US House handed Bush on Friday when it opposed the administration's deployment of additional combat troops to Iraq.

Although Rice used her visit to publicly praise the Iraqi government's role in a new security crackdown in Baghdad, an Iraqi official said she was more critical in private.

Rice told Iraqi leaders that the Baghdad security operation needs to "rise above sectarianism" and noted that no US or Iraqi forces have yet moved into the capital's major Shiite militia stronghold, the Iraqi official said.

The official said Rice told Prime Minister Nouri al-Maliki that the initial stage of the crackdown, which began Wednesday, appeared to focus on Sunni areas and had left Sadr City, stronghold of the Mahdi Army militia, nearly untouched.

The official spoke on condition of anonymity because he is not authorized to release the information to the media.

He said Rice stopped short of accusing the Iraqis of displaying pro-Shiite bias in the operation and said it appeared that the crackdown was going well.

Documents captured during a raid about a month ago show that al-Qaida in Iraq has a carefully planned strategy aimed at downing coalition aircraft using a variety of weapons, said a US defense official, who spoke on condition of anonymity because of the sensitivity of the information.

The official said the documents provide fresh evidence that the al-Qaida insurgency is adapting and posing new threats to US forces. The contents of the seized materials were summarized in an intelligence report analyzing recent helicopter crashes.

The New York Times, which first reported on the intelligence analysis, said militants want to concentrate on air forces. "Attacks on coalition aircraft probably will increase if helicopter missions expand during the latest phase of the Baghdad Security Plan or if insurgents seek to emulate their recent successes," the paper quoted the intelligence report as saying.

In the last month, at least six US helicopters have gone down; five of the crashes were blamed on hostile ground fire. The deadliest was a Black Hawk hit by small arms fire on Jan. 20, killing all 12 soldiers aboard.

On Feb. 2, Gen. Peter Pace, chairman of the Joint Chiefs of Staff, acknowleged that ground fire has been more effective against US helicopters recently. He said he didn't know "if this is some kind of new tactics or techniques that we need to adjust to."

Stakes are high for the plan to bring down violence in Baghdad, both to encourage Iraqis to trust their government and police and to demonstrate progress to an American public increasingly fed up with the war.

Bush's approval rating stands at 32 percent, tied for his lowest standing in Associated Press-Ipsos polling, and most people in the United States find fault with his handling of the nearly four-year-old Iraq war.

"The United States is investing a great deal, most especially the lives of our men and women in uniform, and the American people want to see results and aren't prepared to wait forever to see those results," Rice told reporters.

Although reports from the first day or two of the operation placed Iraqi force participation at 45 percent to 55 percent of full strength, Rice said commanders have told her that Iraqi participation is now as high as 85 percent to 90 percent.

She said the Iraqi government is meeting a test she had set for its commitment to the plan by ensuring that the rules of engagement for the joint forces are equitable and nonsectarian. She said Iraqi leaders are also ably describing and defending the plan to Iraqis.

Rice is the highest-ranking US official to visit Iraq since last month's announcement of the security campaign. Her stop, coinciding with the congressional debate, appeared to reflect a calculation by the administration that focusing on potentially promising developments in Iraq was the best response to the congressional voting.

Meeting with a small group of troops and US Embassy staff inside the old Saddam Hussein-era palace that serves as US headquarters in the fortified Green Zone, Rice referenced the week of bitter debate on Capitol Hill.

"Some do not think that this was the right war to fight, and others think that we in the administration haven't fought this war quite right," but still support US forces and others in harm's way.

"I keep hearing and reading the American people don't want to fight this war anymore. I don't think that's right. The American people want to know that we can succeed," Rice said.

The Bush administration so far has spent more than $350 billion on the war and reconstruction. More than 3,100 US troops have died in the conflict. Bush's approval

Violence in Baghdad has dropped off sharply since the military push began earlier this week. US military planners, however, caution that any attempt to stabilize Baghdad could take months and militants are not likely to leave without a fight.

Ten bodies were reported by the morgue in the capital on Friday, compared to an average of 40 to 50 per day common in recent months, as parts of Baghdad have descended into a lawless jumble of gang killings and sectarian payback.

New checkpoints have gone up around the city, creating long traffic jams as vehicles are searched. Iraqi tanks have pushed into areas where roaming gunmen and militant groups have ruled.

Rice's Iraq visit was a sidelight to a trip otherwise devoted to energizing stagnant peace efforts between Israel and the Palestinians.

That mission was complicated by last week's announced power-sharing pact between the U.S-backed Palestinian President and Hamas militants whom the Bush administration considers terrorists.

Rice will spend several days in Israel, the West Bank and Jordan before reporting on peace prospects at meetings in Europe.