The president will meet U.S. military commanders, the U.S. ambassador, and Iraqi leaders.
Bush was accompanied by Secretary of State Rice and other top deputies, and Defense Secretary Gates arrived in Iraq just ahead of the president.
The Anbar province was chosen for the Bush visit to highlight progress made there in recent months. Al-Asad Air Base is 117 miles west northwest of the Green Zone in Baghdad.
Bush stopped in Iraq en route to the Australia, where he will attend an economic summit.
Concidentally -- or perhaps not -- during the U.S.-led invasion of Iraq in 2003, Australian special forces captured the al-Asad Air Base.
Bush's previous Iraq visits came in June 2006 and November 2003.