- 2003: Invasion -

On March 20, 2003, the US leads an invasion of Iraq after then president George W. Bush accuses Saddam of holding "weapons of mass destruction".

By April 9, US troops capture Baghdad, where a statue of Saddam is toppled by a US tank with the help of a crowd of jubilant Iraqis.

Bush announces the end of major combat operations on May 1.

On October 2, the US admits no weapons of mass destruction have been found.

On December 13, Saddam is captured near his hometown of Tikrit after nine months on the run. He is hanged three years later.

- 2004: Abu Ghraib -

The broadcast in April 2004 of images of torture and other abuse of Iraqis detained at the US-run Abu Ghraib military prison shocks the world, undermining the position of the Americans in Iraq.

Power is transferred to an interim government in June.

- Insurgency, sectarian bloodbath -

In November 2004, more than 10,000 American and 2,000 Iraqi soldiers attack the Sunni Arab city of Fallujah, which has become a symbol of resistance to the occupation, after the lynching of four Americans in March.

In February 2006, Al-Qaeda-linked Sunni extremists blow up a Shiite shrine in Samarra, sparking a wave of sectarian killings that rages until 2008 and leaves tens of thousands dead.

In January 2007, Bush announces the deployment of 30,000 more troops, bringing the total to 165,000, saying the surge is needed to restore control.

- 2009: US starts to go -

In February 2009, new US president Barack Obama, who had opposed the invasion, says most troops will be withdrawn by August 2010.

On December 18, 2011, the last US soldiers leave.

More than 100,000 civilians have been killed since the invasion, according to the Iraq Body Count database. The US lost nearly 4,500 troops.

- 2014: Fighting IS -

In January 2014, jihadists from the Islamic State group capture Fallujah and parts of nearby Ramadi.

In June, they seize the northern city of Mosul and by the end of 2014 hold one-third of Iraq.

The US bombards positions of jihadists that threaten Iraqi Kurdistan and thousands of Christians and Yazidis.

With the help of the US-led coalition, Iraqi forces drive IS from the country's urban centres and, in December 2017, declare victory.

- 2019: Jousting with Iran -

Since the invasion, America's arch-foe Iran has strengthened its influence over Iraq, backing the Hashed al-Shaabi paramilitary force that played a key role in driving out IS.

On December 31, 2019, thousands of Iraqis attack the US embassy in Baghdad to protest a deadly bombing against a Hashed faction.

On January 3, 2020, top Iranian general Qasem Soleimani and senior Hashed commander Abu Mahdi al-Muhandis are killed in a US drone strike in Baghdad.

Iran responds with missile strikes on bases hosting US soldiers in Iraq.

- 2020: US troops start to go -

The Iraqi parliament calls for an end to the presence of foreign troops in the country.

In August, then president Donald Trump says US forces will leave Iraq but gives no date. Troop numbers are reduced from 5,200 to 3,000 in September.

- 2021: Combat mission over -

In July 2021, President Joe Biden said US combat operations in Iraq would end this year, but that soldiers would continue to train, advise and support Iraq's military in the fight against IS.

Some 2,500 US troops remain in Iraq but pro-Iran groups want them out by December 31.

Iraq announces that the coalition's combat mission is over on Thursday, with the transition to a "non-combat mission" to be completed by the end of the year.