The US Senate is this week set to vote to repeal two decades-old war authorisations that provided the legal cover for wars against Iraq .
The so-called Authorisations for the Use of Military Force were passed in 1991 after Iraq invaded Kuwait and in 2002 ahead of the US-led invasion of Iraq the following year.
What is an AUMF? Under the US Constitution, Congress — not the president — has the right to declare war. But to allow a president to respond to a threat, the Senate and House of Representatives can pass an AUMF.
The two that may be repealed this year have been labelled “zombie” authorisations because they never expire but their original purpose no longer applies.
Critics say the AUMFs should be repealed because Iraq is not a US adversary and because they could pave the way for future destabilising military action that has little to do with the original intent of the authorisations.
Some criticised Republican then-president Donald Trump's use of the 2002 Iraq AUMF for the 2020 killing of senior Iranian military commander Qassem Soleimani , who was in Iraq but whose targeting was not connected to the earlier war.
What about the 'War on Terror'? Members of Congress are not — for now — targeting a third AUMF, which passed days after the September 11, 2001, attacks . The measure authorised then-president George W Bush and presidents since then to target Al Qaeda.
Because that AUMF also does not expire and was not limited by geography, it has been used to justify military action around the globe. Lawmakers say the campaign against militant violence is too important to repeal the 2001 authorisation before a replacement is written.
January 29, 2002: US President George Bush identifies Iraq, Iran and North Korea as part of an 'axis of evil' in his State of the Union address. 'States like these, and their terrorist allies, constitute an axis of evil, arming to threaten the peace of the world. By seeking weapons of mass destruction, these regimes pose a grave and growing danger,' he says. Getty
February 15, 2002: Thousands of people gather in Hyde Park in London after finishing a protest against war in Iraq. The march is believed to be the UK's biggest ever peace protest. Getty
March 18, 2003: US and British forces move into position before a possible military strike near the Kuwait-Iraq border. A day prior, Mr Bush gave Iraqi President Saddam Hussein and his sons 48 hours to leave the country or face war. Getty
March 21, 2003: Fires burn in and around Saddam's Council of Ministers during the first wave of US-led coalition airstrikes on Iraq in Baghdad. 'These are the opening stages of what will be a broad and concerted campaign,' he says in an address. The attack begins with a massive air strike campaign named 'shock and awe'. Getty
March 29, 2003: A man and child walk on a road near the entrance of the besieged city of Basra as oil fires burn in the distance. Baath Party loyalists take up positions in Basra, Iraq's second largest city, making it a target of the US-led war on Iraq. Getty
April 9, 2003: Iraq’s capital, Baghdad, falls to US forces. Saddam’s regime loses control as American troops enter the city centre. On May 1, US President George W Bush prematurely declares the end of major combat in Iraq. Reuters
August 30, 2003: A burnt-out car is removed from outside Najaf’s Imam Ali Mosque, the holiest Shiite shrine in Iraq, a day after 87 people were killed in a car bomb attack. The attack raises sectarian tension as thousands of Iraqi Shiites, some of them backed by Iran, demand the right to form militias. Reuters
December 13, 2003: Ousted president Saddam Hussein is found by US troops in a cellar south of Tikrit, near his hometown. 'Ladies and gentlemen, we got him,' says US ambassador Paul Bremer, who was appointed to lead the Coalition Provisional Authority. AFP
March 31, 2004: A car burns in the aftermath of an insurgent attack on Fallujah, in which four Blackwater private security contractors were killed and their mutilated, burnt bodies were left hanging from a bridge. Reuters
May 3, 2004: Coffins of US military personnel killed in Iraq are prepared to be offloaded at Dover Air Force Base in Delaware. Days later, Al Qaeda beheaded US businessman Nicholas Berg and recorded his killing. Reuters
June 28, 2004: US administrator in Iraq Paul Bremer (R), Iraqi Prime Minister Ayad Allawi (C) and the country's most senior judge Midhat Mahmoud (L) smile as the US transfers sovereignty to Iraq in Baghdad. Mr Allawi calls the event 'a historic day' and says that Iraq was 'capable of controlling the security situation'. Reuters
January 30, 2005: Iraqis vote in the first parliamentary elections of the post-Saddam era. Sunnis largely boycott the vote, while most Shiite parties coalesce into a sectarian bloc, cementing divisions within the country. Getty
April 7, 2005: Veteran Kurdish leader Jalal Talabani raises his hands after being sworn in as Iraq's first democratically elected president. Later that month, Shiite Islamist Ibrahim Al Jaafari takes office as prime minister, hailing from the exiled Dawa Party. Getty
July 24, 2005: Burnt-out vehicles at the scene of a lorry bombing outside a police station that killed 22 people in south-east Baghdad. The explosion also injured 25 people, destroyed 22 cars and 10 shops. AFP
October 19, 2005: Saddam’s trial begins. Prosecutors focus on a massacre in the village of Dujail, 100 kilometres north of Baghdad, where about 150 people, including children, were killed following an assassination attempt against the former dictator. Many other charges relate to a genocidal campaign against Kurds during the 1980s, during which Saddam ordered a chemical attack on the town of Halabja, killing up to 5,000 people. Getty
February 23, 2006: Iraqis clean up debris after an Al Qaeda bombing at Al Askariya holy Shiite shrine in Samarra, Iraq. Shiite police and militia members — in many cases indistinguishable — responded by rampaging through Sunni-majority areas, in an onslaught that coalition forces appeared powerless to halt. Getty
June 8, 2006: Maj Gen Bill Caldwell speaks during a press conference as satellite images are shown of a US air strike that killed the leader of Al Qaeda in Iraq, Abu Musab Al Zarqawi, in a joint US-Iraqi raid. Getty
December 30, 2006: Saddam is executed by hanging. The execution and taunting of Saddam before his death is secretly filmed by a witness, stirring further tension within Iraq. Getty
January 11, 2007: US officers watch Mr Bush's speech announcing that another 20,000 soldiers will be sent to Iraq, at Camp Ramadi in Iraq's violent Anbar province. The approach becomes known as the 'Surge,' and envisages a closer partnership between US and Iraqi forces and tribes, as well as American forces being stationed closer to Iraqi communities. Getty
July 12, 2007: Two Reuters photographers and five civilians are killed by a US Apache helicopter in Baghdad. US video footage of the incident would later be released by Wikileaks. EPA
December 14, 2008: Mr Bush makes his final visit to Iraq to sign a co-operation agreement between Iraq and the US known as the Strategic Framework Agreement. At a press conference with Nouri Al Maliki, Munthadar Al Zaidi, a journalist, throws his shoes at Mr Bush. Mr Al Zaidi is severely beaten and jailed for six months. Reuters
February 27, 2009: US President Barack Obama announces Washington’s decision to withdraw most American troops by August 31, 2010. Mr Obama says 50,000 troops will remain for smaller missions and to train Iraqi soldiers. EPA
April 23: At least 80 people are killed in three suicide bombings in Baghdad, making it the biggest daily death toll since early 2008. A woman standing in a group of other women and children receiving aid reportedly set off one of the bombs. EPA
December 21, 2010: Iraqi Prime Minister Mr Al Maliki (L) and members of his newly formed cabinet attend a voting session at the Iraqi Parliament in Baghdad, Iraq. The new government was unanimously approved, ending nine months of deadlock. Getty
JANUARY 8, 2011: Populist Shiite cleric Moqtada Sadr returns to Iraq after four years of self-imposed exile in Iran. In his first public statement, he urges his followers to resist the 'occupiers' of Iraq. EPA
February 25, 2011: A 'day of rage' is declared as tens of thousands of Iraqis protest against Mr Al Maliki’s government. At least 23 people are killed and hundreds injured in a sign of Mr Al Maliki’s growing authoritarianism. Getty
December 17, 2011: The last of the US Troop Brigade board a plane to depart Iraq at Camp Adder, now known as Imam Ali Base, near Nasiriyah, Iraq. Two days prior, the US military formally declared the end of the Iraq War in a ceremony in Baghdad. Getty
December 23, 2012: Protests against harsh security crackdowns break out in Fallujah, Ramadi and Tikrit. Sunni protesters say men are being arbitrarily jailed without evidence while the government holds back pensions for former army officers. The demonstrations last until December 2013 when the Iraqi army tries to break up protest camps. EPA
July 22, 2013: Mourners pray at the coffin of a victim killed during an attack on a prison in Taji, during a funeral at the Imam Ali shrine in Najaf. Reuters
December 22, 2013: Funeral proceedings for a major general of the Iraqi army’s 7th division in Anbar. The division's leadership were killed when a house they are raiding explodes after being rigged with bombs. The mixed Sunni-Shiite group is seen as one of the last non-sectarian units in the Iraqi army. Reuters
June 11, 2014: ISIS fighters stand guard at a checkpoint in the northern Iraqi city of Mosul. Days prior, the militants seized Iraq's second biggest city of Mosul as well as Tikrit, hometown of former dictator Saddam Hussein, and other towns and cities north of Baghdad. Reuters
July 9, 2014: Al Nuri Mosque in Mosul before it was destroyed by ISIS militants during their retreat three years later. On June 29, Abu Bakr Al Baghdadi, leader of ISIS, appeared for the first time in public at the mosque to declare the caliphate. EPA
October 18, 2014: Smoke rises over Syrian town of Kobani after an air strike. Three days prior, Washington launched a campaign called Operation Inherent Resolve. Over the next year, the US military conducts more than 8,000 air strikes in Iraq and Syria. Reuters
November 13, 2015: Kurdish forces seized Sinjar from ISIS after a prolonged siege, in the largest urban battle undertaken by the Kurdish Peshmerga. Getty
October 16, 2006: Iraq launches US-backed campaign to liberate Mosul from ISIS. EPA
October 21, 2016: Fire at an oil field that was set on fire by retreating ISIS fighters before the Mosul offensive in Qayyarah, Iraq. Getty
July 2, 2017: While retreating from Mosul, ISIS destroys Al Nuri mosque. Iraqi forces encounter stiff resistance from ISIS with improvised explosive devices, car bombs, suicide bombers, heavy mortar fire and snipers hampering their advance. Getty
July 9, 2017: Iraqi Prime Minister Haider Al Abadi declares victory over ISIS in Mosul. In December, he declares full victory over ISIS. AFP
Will the repeal be passed this time? Congress has tried and failed to repeal AUMFs repeatedly over the past 10 years.
Backers say things are different this time, partly because it has been 20 years since the last Iraq war began, and because Democratic President Joe Biden has said he supports the repeal and does not believe it will harm national security.
The measure has both Democratic and Republican co-sponsors in both the Senate and House. It is expected to easily pass the Democratic-led Senate.
Its fate in the Republican-led House is less clear, given that support for AUMF repeals in the past has been much stronger among Democrats than Republicans.
Republican House Speaker Kevin McCarthy said this month there was a strong chance the House would pass a bill.
Updated: March 28, 2023, 10:42 PM