President Bush has rejected calls for withdrawing U.S. troops from Iraq, saying it would be a "huge mistake" at this point.
At a news conference on Monday, Mr. Bush said that leaving the country now would send the wrong message to reformers in the Middle East, and embolden Iran and extremists.
He added he is committed to securing peace in Iraq and strengthening its government, saying a failure in Iraq would threaten the security of the United States.
The president said U.S. military commanders are continuing to adjust their tactics to prevent attacks by terrorist groups and end violence among sectarian groups.
Some U.S. lawmakers have been calling on the president to set a date for withdrawing U.S. troops from Iraq.
In Iraq, the U.S. military says four American service members have been killed in combat in the past 24 hours.