The Iraq War was a protracted armed conflict from 2003 to 2011 that began with the invasion of Iraq by the United States–led coalition which overthrew the authoritarian government of Saddam Hussein. The conflict continued for much of the next decade as an insurgency emerged to oppose the coalition forces and the post-invasion Iraqi government. An estimated 151,000 to 1,033,000 Iraqis died in the first three to five years of conflict. US troops were officially withdrawn in 2011. The US became re-involved in 2014 at the head of a new coalition; the insurgency and many dimensions of the armed conflict continue. The invasion occurred as part of the George W. Bush administration's War on Terror following the September 11 attacks despite no connection of the latter to Iraq.
In October 2002, Congress granted President Bush the power to decide whether to launch any military attack in Iraq. The Iraq War began on 20 March 2003, when the US, joined by the UK, Australia, and Poland launched a "shock and awe" bombing campaign. Iraqi forces were quickly overwhelmed as coalition forces swept through the country.