Mar 28, 2008 -WASHINGTON — President 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 Shiite 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…