OSAN AIR BASE, South Korea — His war policies under siege at home, President Bush said Saturday there would be no early troop withdrawal because "sober judgment" must prevail over emotional calls to end the military mission before Iraq is stabilized.

"We will fight the terrorists in Iraq. We will stay in the fight until we have achieved the victory that our brave troops have fought for," Bush told thousands of American troops spilling out of a cold hangar at this U.S. military installation 40 miles south of Seoul. "The defense of freedom is worth our sacrifice."

The speech added the president's voice, from thousands of miles away, to a nasty debate in Congress over his Iraq policies and the timing of any U.S. withdrawal. It also continued a rapid-fire White House counterattack against the president's newly aggressive war critics.

Bush spoke at the end of a three-day stay in South Korea, laying over here for little more than an hour after meetings with 20 other Pacific Rim leaders in Busan, South Korea. Immediately after speaking, he left for China — the most anticipated segment of his weeklong Asian swing.

Democrats have seized on the indictment of a top White House aide in the CIA leak case to question whether the president deceptively portrayed prewar intelligence on whether Saddam Hussein had weapons of mass destruction.

Some Republicans on Capitol Hill have become willing to question Bush on Iraq — albeit carefully — amid fears that the public's concerns will affect next year's midterm congressional elections.

Earlier this week, the GOP-controlled Senate voted down a Democratic push for Bush to outline a withdrawal timetable, but supported telling the president to outline a strategy for "the successful completion of the mission" in Iraq.

Washington's weeklong clash over Iraq policy continued Friday, fueled by the call from prominent defense hawk and decorated Vietnam war veteran, Rep. John Murtha, D-Pa., for the nearly 160,000 troops to be brought home.

The fireworks prompted Bush to insert lines into his long-planned speech to troops. The White House released them nine hours before Bush delivered his speech in Saturday's early morning hours East Coast time, to ensure they would make newspaper deadlines and evening newscasts back home.

The president said a pullout from Iraq would create a home base for terrorists to launch attacks on the United States and moderate Arab nations.

"In Washington, there are some who say that the sacrifice is too great, and they urge us to set a date for withdrawal before we have completed our mission. Those who are in the fight know better," Bush said. "So long as I am the commander in chief, our strategy in Iraq will be driven by the sober judgment of our military commanders on the ground."

Before flying to the base, Bush attended the closing meetings of the annual Asia Pacific Economic Cooperation forum in the gritty port city of Busan. The 21 APEC leaders hoped to inject urgency into badly stalled global talks on a worldwide free-trade accord by pushing Europe to make key concessions. They also pledged unity in preventing a potential bird flu pandemic and combatting terrorism.

Now Bush turns to a two-day state visit in China, a strategically key nation. The communist giant is a vast and growing market for American goods, undertaking a military buildup that worries U.S. officials and using its economic might to increasingly assert itself globally.

Taking center stage in Sunday's meetings with Chinese President Hu Jintao are bird flu fears — China reported its first human cases this week — and sticky trade issues. The United States is demanding that China complete moves toward a market-based currency, address an enormous trade imbalance, and follow through on promises to better protect copyrights of American software and movies.