President George W. Bush said Friday that the flare-up in violence in oil-rich southern Iraq and parts of Baghdad presents "a defining moment in the history of a free Iraq" as the government there seeks to root out Shi'ite militias. Bush made clear that the United States stands firmly behind Iraqi security forces and Prime Minister Nouri al-Maliki. "He made the decision to move and we'll help him," the president said. "It's going to take awhile, but it's a necessary part of the development of a free society," Bush said at a White House news conference with visiting Australian Prime Minister Kevin Rudd. At the same time, the president said the situation in Iraq remains "dangerous and fragile." His comments followed US air strikes in both the southern city of Basra and in a Shi'ite militia stronghold in Baghdad. The renewed violence came as tensions rose among followers of radical Shi'ite cleric Muqtada al-Sadr angry over a crackdown that has threatened to unravel a militia cease-fire.