The United States invaded Iraq in March 2003 under the direction of President George W. Bush to depose Saddam Hussein from power. After months of fighting, Hussein's regime was overthrown and he was eventually captured and executed. However, violence in Iraq continued for years as Sunni and Shiite groups fought for control. Bush argued that the ongoing military presence was necessary to prevent terrorist groups from gaining control of Iraq's oil fields and using the country as a base for attacks.