"Are you here to work or… work?" a Basra airport security guard asked sympathetically. I was standing on a small wooden platform behind a flimsy curtain, as she waved her hand-held metal detector across my body.

She had guessed my North African origins from my features and my accent, and was, I suppose, trying to make sense of the fact that I had arrived in Basra, in May 2010, alone.

"Good God!" I thought. I was in Iraq to conduct research on human security in Basra, for a research project at LSE.

Before I could answer, she directed me out of the cubicle with a sentiment that I was to hear repeated, albeit in different combinations of words, over the coming days.

"Don't worry, there's no shame in it, or anything here anymore. We have fallen so far. We are alive but not living.

"May God be with you, my sister."

Every Basrawi I spoke to judged that the US invasion had made an emphatically negative impact on their lives. They spoke of daily killings, the brutalisation of society, the decimation of infrastructure, a sharp rise in birth defects and domestic violence, soaring unemployment, particularly among young men, rampant rape and crime, and corruption levels unmatched by Saddam and his henchmen. The dominant motif was nostalgia for the Saddam era, even here, among communities which had fared worst under the Baathist regime.

By the most conservative estimates, 100,000 Iraqis perished in the invasion and its bloody aftermath, with large scale attacks continuing to this day. A recent report by Stuart Bowen, the Special Inspector General for Iraq Reconstruction, found that a good deal of $60bn spent by the US on rebuilding Iraq (that is, $15m a day for nine years) had been stolen or wasted. Despite a national budget of $100bn, the everyday grind in Iraq is exacerbated by woeful standards of service delivery, particularly with regard to electricity and sanitation. But how was the violent imposition of new dynamics in Iraq justified by the Bush administration in 2003, and which of its arguments have stood the test of (a decade of) time?

Weapons of mass destruction

The Bush administration's principal stated justification for the invasion of Iraq in 2003 was to "disarm" Saddam Hussein of his WMD.

A sophisticated case rendered the Iraqi stockpile both knowable and unknowable simultaneously. Bush administration officials offered detailed catalogues of deadly materials, including 25,000 litres of anthrax, 500 tonnes of sarin, VX nerve agents, 38,000 litres of botulinum toxin, Scud-variant ballistic missiles, and five different methods of enriching uranium for a nuclear bomb. That Saddam possessed and concealed these dangerous weapons was said to be beyond doubt (Cheney, August 27, 2002; Powell, February 5, 2003; Bush, March 17, 2003).

Yet this certainty was coupled with a subtle case for the inherent mysteriousness of the stockpile, which both heightened the perception of danger and lowered the burden of proof. The regime was said to be moving its arsenal, tunnelling underground and "housecleaning" to evade inspectors. The secretive nature of Saddam's regime was also invoked as mitigation for the absence of iron-clad proof - "the first time we can be completely certain he has nuclear weapons is when, God forbid, he uses one" (Bush, September 12, 2002).

The WMD assertion was also pivotal to the attempt to justify the war along the lines of conventional self-defence, through the doctrine of pre-emption. Although no Iraqi attack on the US was imminent, the Bush administration employed an expansive conception of threat - to "civilisation" and to our "way of life" - which was used to finesse the distinction between pre-empting an imminent attack, largely regarded as legitimate in the just war tradition, and the more dubious doctrine of preventive warfare. Bush explicitly adapted the concept of "imminent threat" by invoking the disproportionately destructive nature of WMD. He argued that the existence of such weapons required that the US confront threats before they fully materialise.

There had been serious doubts about the viability of the Bush administration's intelligence about WMD before the war commenced, and no evidence of WMD was later uncovered in Iraq. Douglas Feith's insistence in 2004 that "no one can properly assert that the failure, so far, to find Iraqi WMD stockpiles undermines the reasons for war" was jarring, given that disarming Saddam of WMD was the principal reason for war, and that the WMD claim was integral to the argument for pre-emptive self-defence.

The al-Qaeda connection

The WMD issue was also crucial to the second strand of Bush's case for war, which was to assert a link between Iraq and the perpetrators of the 9/11 attacks. The claim was made so forcefully that, five months after the invasion of Iraq, a Washington Post poll found that almost 70 percent of Americans believed Saddam was personally involved in the 9/11 attacks.

Iraq was said to be a material ally of al-Qaeda. The Bush administration posited a "sinister nexus" between Saddam and Osama bin Laden's men, involving an alliance dating from the 1990s, combined training in biological and chemical weaponry, and clandestine meetings in Prague. But in reality, in the words of former counterterrorism specialist Dick Clarke, "there's absolutely no evidence that Iraq was supporting al-Qaeda, ever".

A second feature of the Bush administration's link between Iraq and al-Qaeda was an implied ideological affinity. According to Bush, there was such a thing as an "ideology of terror", and it was suggested that the Baath party and the al-Qaeda network shared it. However, while Baathism's ideological aims were secular, socialist and pan-Arab, al-Qaeda's objectives were religious, fundamentalist and pan-Islamic, involving a global insurgency aimed at subverting the institution of the nation state. In fact, bin Laden had railed against Saddam Hussein since the early 1990s, denouncing him as a thief and an apostate, and declaring the Baath party to be infidel. At the same time, excessive religiosity was seen as threat to Iraqi national unity, and Saddam was well known for his brutal crackdowns on clerics and their families.

The third element of the Iraq-al-Qaeda connection was the implication that Saddam and his cronies were themselves "terrorists". Shortly after 9/11, the Bush administration began referring to "the terror regime in Iraq", eliding the difference between the way in which a dictator terrorises his own population and terrorism, as it is conventionally understood. Rumsfeld exemplified this well when he spoke of "the tyranny of terrorism", just as Wolfowitz took to describing Iraq's alleged WMD stockpile as "weapons of mass terror".

Dick Cheney's prognosis that an Iraq invasion would mean "extremists in the region would have to rethink their strategy of jihad" was disputed before the invasion (for example, Jacques Chirac: "a war of this kind… would create a large number of little bin Ladens") and challenged by events after it. Bin Laden himself viewed the US invasion of Iraq as "a golden and unique opportunity". In the context of a political power vacuum, and on the back of an insurgency catalysed by a newly disenfranchised Sunni community, jihadi groups proliferated in Iraq - and continue to wreak havoc, 10 years on.

Liberating Iraqis

Bush's first two arguments for war were widely doubted before the invasion, and disproved shortly afterwards. Since 2005, the dominant justification for the invasion of Iraq has been the overthrow of a vicious regime and the rescue of the Iraqi people from oppression. But this is problematic.

The Iraq invasion cannot be reasonably described as a case of "humanitarian intervention" for three reasons. The means used in the war - a "shock and awe" bombing campaign, including the use of cluster munitions in populated areas - were clearly not designed with the objective of safeguarding Iraqi civilians. Secondly, there was no evidence of the triggering mechanism for a humanitarian intervention, such as mass slaughter or crimes that shock humanity. Saddam had a terrible track record but, during the run-up to war, no such crimes were ongoing or imminent. Third, humanitarian motives were clearly not dominant, as the war would probably not have occurred in the absence of the issues of WMD and/or the al-Qaeda connection. During his February 2003 presentation to the UN, even Colin Powell's slidesrelated to Saddam's human rights violations were labelled, "Iraq: Failing to Disarm".

"The forms of democracy and pluralism are present through provincial and national elections, but their substance is elusive."

More importantly, however, Iraqis continue to labour under the shadow of authoritarianism. The forms of democracy and pluralism are present through provincial and national elections, but their substance is elusive. Saddam he is not, yet President Nouri al-Maliki presides over secret jails and torture sites, arbitrary arrests and detention without trial, unprecedented levels of corruption, discriminatory laws, the politicisation of the judiciary and the security forces, and the entrenchment of sectarianism. In recent months, he appears to have accelerated the move to concentrate power in his own hands.

These dark continuities have been coupled with the new realities of persistent insecurity - that is, Iraqis have been suspended between the abuses of Maliki's "strong" state and the prospect of state collapse.

Albeit on a lesser scale, the inter-communal violence sparked by the downfall of Saddam, and the Bush administration's failure to prepare for its aftermath, is currently on an upward curve. Last year brought a number of coordinated high casualty attacks, involving roadside bombings, mortars and rockets, with a death rate of between 150 and 350 per month.

The Iraq Security Forces, which is comprised of 700,000 men and which recently purchased 36 F-16 fighter jets from the US, appear weak in the face of a resurgent al-Qaeda in Iraq, which enjoys increasing freedom of movement throughout the country. The aim is to destabilise the government through constant attacks and to capitalise on the sectarian undertones of the crisis in Syria and the al-Anbar protests. Iraq is increasingly caught in the crosshairs of the showdown between Bashar al-Assad and his local and international opponents. Beyond the (Shia) government's support for the (Shia) Assad regime, an alliance determined to some extent by Maliki's closeness to the Iranians, more than 42 Syrian army soldiers were massacred on Iraqi soil on March 4. In a hateful sectarian diatribe, al-Qaeda in Iraq claimed responsibility for the attack.

At the same time, a domestic crisis is brewing. Chanting "Either Iraq or Maliki!", tens of thousands of protesters in the mainly Sunni al-Anbar province have pitched tents and blocked highways, decrying the government's marginalisation of Sunni leaders, its draconian anti-terror laws, widely seen as targeting the Sunni sect, and its corruption and inefficiency. Iraq's Kurdish authorities in the North of the country have also engaged in a stand-off with the Maliki government, centred on decision-making rights regarding oil contracts, internal border disputes, and wider disaffection with Maliki's centralising tendencies. "He is proceeding with violating the foundations of the constitution on a daily basis", said Kurdish MP Mahmoud Othman.

Optimistic readings of the situation in Iraq, 10 years on, will focus on the end of Saddam Hussein's reign of terror, the existence of elections and the export of 2.5 million barrels of oil a day. Tony Blair would go further, suggesting, as he did, that, had there be no invasion, Iraqis would have moved to topple Saddam and the situation would look "a lot more like Syria" - as though the tragedy of the Iraq invasion and its aftermath were not comparable to Syria, in terms of the numbers of dead, maimed, disappeared and made homeless, the trafficked children, the war widows forced into begging or prostitution, the lost generation of men. As though the poisonous dynamic of a foreign and largely unwanted occupying presence were incidental to the persisting cycles of bloodshed, and our ultimate responsibility irrelevant to the moral balance.

I corrected the security guard at Basra airport. Not about the lady of the night assumption, which was amusing and neither here nor there as far as I was concerned. Instead, I admitted I was a US citizen. "You didn't fall," I said. "We pushed you."

Dr Alia Brahimi is a Visiting Research Fellow at the University of Oxford. She received her doctorate from the University of Oxford in 2007.