AL ASAD AIR BASE, Iraq (CNN) -- President Bush made a surprise visit to an Iraqi air base Monday, saying fewer U.S. forces may be able to maintain security at its current level.
President Bush salutes Gen. David Petraeus, left, after arriving Monday at an air base in Iraq.
"Gen. [David] Petraeus and Ambassador [Ryan] Crocker tell me if the kind of success we're now seeing continues, it will be possible to maintain the same level of security with fewer American forces," Bush said during remarks at Al Asad Air Base in Anbar province.
But Bush later warned Washington war critics who are pushing for quick troop withdrawals to temper their expectations.
During a rally for troops at the base, Bush said any pullout would be made from a position of "strength and success."
The White House is due to deliver to Congress next week an assessment on Bush's increase of 30,000 troops to Iraq this year.
"People shouldn't jump to conclusions until the general and the ambassador report," Bush said. Watch Bush's remarks about U.S. troop levels in Iraq »
During a rally later for more than 600 American troops at the base, Bush warned members of Congress who might be anticipating quick reductions in U.S. forces.
"Those decisions will be based on a calm assessment by our military commanders on the conditions on the ground, not reaction by Washington politicians to poll results in the media," said Bush. "In other words, when we begin to draw down troops from Iraq, it will be from a position of strength and success, not from the position of fear and failure."
Praising the troops, Bush said, "every day you show bravery under incredibly difficult circumstances. I'm incredibly proud to be the commander in chief of such a great group of men and women."
The excited crowd responded to their commander in chief with hearty cheers and shouts of "ooh-rah!" and "hoo-ah!"
Bush met earlier with Iraqi Prime Minister Nuri al-Maliki. He also met with Anbar tribal leaders hailing their cooperation with U.S. forces as a success in fighting al Qaeda in Iraq.
"The level of violence is down, local governments are meeting again, police are in control of the city streets and normal life is returning," said Bush.
The president credited Anbar citizens who "rejected the dark vision of al Qaeda" and "organized themselves and they took on the terrorists."
"The result was that many local leaders who had once fought against our forces began to fight alongside our forces and against al Qaeda," Bush said.
"They didn't like idea of murderers deciding their fate," he said.
Earlier, Air Force One touched down under a blazing sun for the six-hour visit.
After exiting the aircraft, Petraeus, the top war commander, and others welcomed Bush with smiles, salutes and handshakes in the 115- degree heat.
The White House denied the trip was a publicity visit ahead of a report about U.S. troop increases in Iraq to be delivered by Petraeus next week in Washington.
Advisers said the trip was so Bush could have face-to-face meetings with al-Maliki and local Sunni leaders in an effort to move them closer toward political reconciliation.
Some U.S. lawmakers have criticized al-Maliki's Shiite-led government for not reconciling with Sunni groups, but Bush has stood by the Iraqi leader and fended off calls for his resignation.
Democratic Sen. Majority Leader Harry Reid's spokesman Jim Manley released this statement: "Every objective assessment has shown the president's flawed Iraq strategy is failing to deliver what it was supposed to: a political solution for Iraq.
"After nearly five years, over 3700 American lives lost, and at a cost of more than a half a trillion dollars, it is time Republicans recognize the reality on the ground, stand up to President Bush and help Democrats bring a responsible end to the war."
Bush's visit to Iraq "will not change the debate in Washington at all," a Democratic leadership aide told CNN on Monday.
Many members of Congress traveled to Iraq themselves in August. Those trips and reports "about the lack of political progress in Iraq mean much more than a surprise visit by the president," the aide said.
After commanders greeted the president on the tarmac, Bush posed for pictures before being driven in a motorcade to a concrete building on base where a Marine gave him a short briefing with about 20 other troops in fatigues.
"How is morale?" asked Bush.
"Very high, sir," said the unidentified Marine.
Far to the south in the Iraqi city of Basra, 500 remaining British troops completed a pullout Monday, a move that Britain said did not represent a major policy shift but a long-planned handover to Iraqi forces.
Monday's visit is Bush's first trip to Iraq outside of Baghdad. The president also traveled to Iraq in 2003 and 2006.
Al Asad Air Base dates to the 1970s, when it was used by Iraqi forces loyal to Saddam Hussein. It houses about 10,000 U.S. troops, mostly Marines. The facility was captured in April 2003 by Australian special forces. See map showing location of base »
Measuring about 17 miles in circumference, the base is located not far from the Euphrates River between Baghdad and the Syrian border, where the Bush administration has said many foreign fighters have crossed into Iraq.
The president stopped in Iraq en route to the Asia-Pacific Economic Cooperation summit in Sydney, Australia.
Bush is accompanied on the Iraq visit by Lt. Gen. Douglas Lute, the newly appointed White House official responsible for coordinating Iraq issues.
Also joining Bush on the Iraq visit are U.S. Secretary of State Condoleezza Rice, national security adviser Stephen Hadley, Defense Secretary Robert Gates and Joint Chiefs Chairman Gen. Peter Pace.
The president was spirited out of the White House late Sunday and driven to Andrews Air Force Base, Maryland.
Instead of the usual presidential motorcade, only one other car accompanied Bush's limousine from the executive mansion to Andrews in an effort to maintain the subterfuge.
Sixteen hours before he was scheduled to leave for the Asia summit, Bush boarded Air Force One as it sat in a hanger and the aircraft departed after dark.
White House press secretary Tony Snow said a false schedule released for the news media on Monday was part of the security plan for the trip. E-mail to a friend
CNN's Ed Henry, Elaine Quijano, Jessica Yellin and Mike Maltas contributed to this report.