The Iraq War began with the 2003 invasion of the country by a US-led coalition. The fighting continued until the end of the decade and some time after as an insurgency emerged to oppose the occupying forces and the post-invasion Iraqi government. The last convoy of US troops exited Iraq in mid-December of 2011.

The US invasion began on March 20th, 2003, which toppled the government of Saddam Hussein. The following power vacuum led to widespread sectarian violence between Shias and Sunnis, as well as a lengthy insurgency against US and coalition forces.

In August, the Canal Hotel bombing killed at least 22 people, including the UN Special Representative in Iraq, and wounded over 100. The bombing resulted in the withdrawal within weeks of most of the 600 UN staff members in Iraq.

In 2005, Iraq formed its new government after holding multi-party elections. 160-thousand US troops were to deployed in Iraq. In 2007, the battle of Haifa Street, a two-mile-long street in downtown Baghdad, pitted US and Iraqi army forces against various Sunni insurgents. There were heavy casualties on both sides.

In December 14th, 2008, the US and Iraq signed the Status of Forces Agreement, which established that all US combat forces would be completely out of Iraq by the end of 2011. Prior to the withdrawal, the Obama administration sought to establish US military bases in Iraq and gain legal immunity for US forces in the country following the exit. Iraq refused these requests.

From 2003 through the end of 2011, about a million US military personnel were deployed to Iraq. Nearly 4,500 were killed. In 2014, the rise of Islamic State in Iraq, as well as in Syria, triggered a new US-led military mission in Iraq. And Iraq remains a cauldron of violence, with hundreds of thousands of Iraqis dead due to the invasion and subsequent war.