The former US administrator in Iraq said on Wednesday his biggest regret was not getting a grip on the country's dangerous security situation before the formal transfer of authority to Iraqis.
Speaking outside the White House, Mr Paul Bremer said he was very relieved to be back in America after quietly handing over sovereignty to a new Iraqi interim government on Monday.
"It's like having a rather large weight lifted off my shoulders," he said in an interview with ABC's Good Morning America show.
But Mr Bremer said he was sorry not to have brought more stability to Iraq, where insurgents launch daily attacks and the death toll is rising for US forces and Iraqis.
"The greatest regret has to be that we were not able to get the security situation under better control by the end of the occupation," said Mr Bremer.
Despite not being able to get a grip on security, Mr Bremer said he believed Iraq was a better place after 14 months of US occupation and the ouster of President Saddam Hussein.
Still wearing trademark combat boots and a dark business suit, Mr Bremer was optimistic Iraq's interim government would be successful and hailed Prime Minister Iyad Allawi as a "tough guy" with a very able Cabinet.
"Saddam's henchmen tried to kill him in the middle of the night, four o'clock in the morning. Two of them arrived with axes and tried to kill him. Almost severed his right leg, severely wounded him and his wife. He spent a year in prison. He came back. He is a tough guy," he said.
"This is going to be a difficult period in the months ahead but I'm confident they're going to succeed," he added.
He welcomed the handover of Saddam to Iraq's legal authorities on Wednesday and said he would get the kind of justice denied his own people.
"It symbolizes how much better this country is today than it was a year ago when Saddam and his tyrants still had their hands at the throats of the Iraqi people. They are going to be very pleased to see him stand trial," Mr Bremer told NBC's Today show.
Saddam is the legal responsibility of the new Iraqi authority but is still in the physical custody of US forces.
Asked whether he feared when Saddam was finally handed over physically to the Iraqis, his supporters would try to overrun a prison and free him, Mr Bremer said: "The more likely scenario is that a bunch of people who want to kill him take him over and hack him to pieces.
"We will hold onto him until we are confident the Iraqis can handle him."