US President George W. Bush hailed Saddam Hussein's execution as "an important milestone" on the road to building an Iraqi democracy but warned it will not end deadly violence there."Saddam Hussein's execution comes at the end of a difficult year for the Iraqi people and for our troops," Bush said in a statement released as he prepared to usher in 2007 at his Texas ranch."Bringing Saddam Hussein to justice will not end the violence in Iraq, but it is an important milestone on Iraq's course to becoming a democracy that can govern, sustain, and defend itself," he said.Bush learned at 6:15 pm (0545 IST) from US national security adviser Stephen Hadley that Saddam would go to the gallows in a few hours, but was fast asleep when the execution occurred, said White House spokesman Scott Stanzel.The ousted dictator was hanged around 9:00 pm Texas time (0830 IST), Iraqi officials said, as the violence-wracked country braced nervously for possible reprisals by his remaining supporters."The president concluded his day knowing that the final phase of bringing Saddam Hussein to justice was underway," Stanzel told reporters.Asked whether that meant Bush was asleep when it happened, Stanzel replied: "That's correct." Taking aim at critics of the special judicial process that led to Saddam's conviction, Bush emphasised that he "was executed after receiving a fair trial -- the kind of justice he denied the victims of his brutal regime."Fair trials were unimaginable under Saddam Hussein's tyrannical rule. It is a testament to the Iraqi people's resolve to move forward after decades of oppression that despite his terrible crimes against his own people, Saddam Hussein received a fair trial."