Flying away from the dusty war zone in Iraq to an Asia summit, US President George W. Bush flirted with the idea that US troop strength could be reduced if security across Iraq improves as it has in Anbar Province, once rife with insurgents. The president told reporters aboard Air Force One on Monday night that his strategy sessions with US and Iraqi leaders and chats about morale with soldiers and Marines at an air base in western Iraq left him hopeful that positive change is starting in the four-year-old conflict. The question, he said, is, "Will it last?" Bush is nearing a decision on how long to maintain the current US troop buildup. He sent 30,000 additional US troops to Iraq to enhance security in Baghdad and Anbar Province. Despite military successes, political progress - especially at the national level - is lagging and Democrats and some prominent Republicans want troops called home. "How many troops does it take to protect us?" Bush asked. "What does it take to have this Iraqi democracy succeed?" Bush left Iraq and headed to Sydney, Australia, for the Asia Pacific Economic Cooperation forum. Debate over the war will most certainly follow him there. He begins talks Wednesday, meeting with Australian Prime Minister John Howard, who joined with Bush and Tony Blair, the former British prime minister, in the invasion of Iraq. Howard is facing an aggressive election challenge from opposition leader Kevin Rudd, and Rudd's desire to pull Australian troops out of Iraq will surely be broached in the talks. Bush also is scheduled to meet with leaders from Japan, China, Russia and South Korea. Some have dubbed this year's APEC the "China summit," a reference to Beijing's rising influence. "Is this a China summit? The answer is absolutely not," Bush said. The presidential entourage had barely climbed aboard Air Force One, leaving dusty desert footprints on its blue carpet, when Bush invited reporters to a conference room for a 30-minute chat. He fiddled with a paper clip as he talked about his day at Al-Asad Air Base, a Saddam Hussein-era airfield now home to 10,000 US troops, who down bottle after bottle of water in sweltering 100-plus degree heat. It was Bush's third surprise trip to Iraq. The first two were to Baghdad. This time he landed in the Iraqi desert, more than 100 miles west of the capital, to get on-the-ground briefings from advisers, including Gen. David Petraeus, the top US commander in Iraq, and Ryan Crocker, the US ambassador to Iraq. Crocker and Petraeus are to testify before Congress next week. Their assessment of the conflict, along with a progress report the White House must give lawmakers by Sept. 15, will determine the future course of the war. "General Petraeus and Ambassador Crocker have said that if the security situation continues to improve the way it has, we may be able to achieve the same objectives with fewer troops," Bush said. He emphasized the word "if." And he didn't say how many troops could be withdrawn, or when. Bush has refrained from thinking aloud about troop deployments. The president said security improvements in Anbar, where local sheiks have joined with US forces against al-Qaida, have given him confidence to "speculate on the hypothetical" - something he repeatedly refuses to do in answering reporters' questions. Bush said he quizzed the troops - who cheered him and Secretary of State Condoleezza Rice with shouts of "Hooh-rah!" - about morale. He said some soldiers and Marines complained that rotations were tough on their families, but added, "I wasn't alarmed by what I heard." Asked if the discussions would affect his decision about troop levels, Bush turned resolute. "The main factor that will affect my decision on troop levels is, can we succeed? What does it take to succeed?" Bush said, chopping the table with the side of his hand. "Because failure would lead to harm to America, is what I believe. As a matter of fact, I'm certain of it." The president described his meeting at the base with Iraqi Prime Minister Nouri al-Maliki as "comfortable." He said the underlying question about the Iraqi government was: "Will this government go after killers?" Meeting with al-Maliki, a Shiite, in the heart of mostly Sunni Anbar province was intended to show the administration's war critics that the beleaguered Iraqi leader is capable of reaching out to Sunnis, who ran the country for years under Saddam Hussein. Bush reiterated his frustration about the slow pace of political progress, yet expressed continued support for al-Maliki, a man Bush said was "still evolving as a leader." He said he addressed his comments to all the Iraqi leaders, but took al-Maliki aside and told him: "You're my friend" and pressed the prime minister and his Shiite and Kurdish allies to entice moderate Sunnis into a new alliance formed last week to try to save the government from collapse. "My message to Maliki is: `You've got a lot of work to do and whatever decision is made in Washington, D.C., is all aimed at helping you achieve what is necessary to get the work done,"' Bush said.