Next week, the top U.S. commander in Iraq and the U.S. ambassador in Baghdad are to testify before Congress. Their assessment of the conflict, along with a progress report the White House must give lawmakers, will determine the next chapter of the war. Top advisers joined Bush, including his national security adviser, Stephen Hadley. Defense Secretary Robert Gates traveled there separately. Bush was scheduled to leave for Australia today for an economic summit with Asia-Pacific leaders, but Air Force One took off from Andrews Air Force Base last night instead. It's usually pretty hard to miss when the president leaves the White House, amid all the sirens and flashing lights of his long motorcade. But that changes when he's trying to move unnoticed, like on an unannounced trip to Iraq. The White House says the president snuck out a side door last night and left the mansion's grounds accompanied by only one other vehicle instead of a motorcade on the way to Andrews Air Force Base. Air Force One took him from there to Iraq. Reporters making the trip weren't told until the weekend, and were only allowed to inform one editor and their spouse. The Associated Press contributed to this story