The United States was right to invade Iraq, but choices made after the initial invasion have eroded security in the country, President Bush said in a television interview to be broadcast today.
"I think history is going to look back and see a lot of ways we could have done things better," Bush said in the interview, which will be aired on CBS' "60 Minutes" program.
Questioned about the current instability in Iraq, Bush said, "Well, no question decisions have made things unstable."
But he maintained that invading Iraq in 2003 was the right thing to do.
"My decision to remove Saddam Hussein was the correct decision, in my judgment," he said. "We didn't find the weapons we thought we would find, or the weapons everybody thought he had. But he was a significant source of instability."
"Iraqi people owe the American people a huge debt of gratitude," he said.
Bush's comments come as his new plan to send 21,500 additional U.S. troops to secure Iraq's capital and shore up forces fighting the insurgency in Al Anbar province is attracting sharp criticism from members of Congress.
In his Saturday radio address, Bush also said his new plan could succeed, because "American forces will have a green light to enter neighborhoods that are home to those fueling sectarian violence."
U.S. forces have been restricted by the Iraqi prime minister from operating freely in the Sadr City area that is home to Shiite cleric Muqtada Sadr's Al Mahdi militia. But Bush said those restrictions had been lifted and that Iraqi Prime Minister Nouri Maliki had promised that he would not tolerate interference with security operations.
Bush also challenged members of Congress who were critical of the plan to come up with their own proposals.
"To oppose everything while proposing nothing is irresponsible," he said.
But Rep. Timothy J. Walz, a newly elected Democrat from Minnesota who served in the war in Afghanistan, called Bush's plan "a step in the wrong direction -- more of the same at the very time we need a new direction in Iraq."
"We need diplomatic and political solutions in Iraq, not more American troops," he said in the Democrats' Saturday radio address.
Many Iraqi leaders also have attacked the plan.
Sadr has emerged as one of the fiercest critics of the continued American presence in Iraq.
In a news conference Saturday in Najaf, Sadr representative Sheik Abdul Razzaq Naddawi warned Bush "not to commit foolishness" and attack Sadr followers.
If they are attacked, he said, "the Shiites will become an explosive belt."
"Anyone who is attacked must respond," Naddawi said. "In Islam, we must respond."
In Baghdad Saturday, police patrols discovered 37 bodies, all of the victims middle-aged men apparently killed by gunfire. Some of the bodies showed signs of torture. In southeast Baghdad, a woman was killed by a mortar round.
In the southern Iraqi town of Samawa, police said that gunmen killed three brothers, and that the charred body of an Egyptian employee of the municipal government was discovered in a trash bin.
Three mutilated corpses were discovered in the southern city of Kut, among them that of a beheaded Iraqi soldier. Kut morgue officials also reported that a police officer was killed while traveling home from work.
Gunmen in Samarra, north of Baghdad, killed a prominent Sunni Arab cleric and political party operative in front of his house, and in a separate incident a policeman was shot to death.
Savage reported from Washington and Moore from Baghdad. Special correspondents in Baghdad and Kirkuk, Najaf, Kut, Samarra, Samawa and Hilla, Iraq, contributed to this report.