Twenty years after the start of the Iraq War, one question remains difficult to answer convincingly. Just why did the United States, under President George W Bush, invade and occupy Iraq? Answers from academics and think tanks range from the need to safeguard oil supplies held by a rogue state that had taken over Kuwait and now controlled a fifth of the world’s oil reserves, through to Iraq supporting terrorism and developing weapons of mass destruction.

Such answers may be plausible enough and include a degree of truth, but we still have to ask: why go to war then? It was barely a year since the US and a few partners had terminated the Taliban regime in Afghanistan. The US had defeated and dispersed the al-Qaeda movement behind the 9/11 attacks, so if the so-called ‘war on terror’ was over, why take on Iraq?

The US domestic political context is important here. Democrat president Bill Clinton had served two terms from 1993 to 2001, and over that time a hard-right vision had emerged within the Republican Party.

Those within this prominent faction – known as neoconservatives – were utterly convinced that Clinton had been a disaster. As they saw it, the collapse of the Soviet Union at the start of the 1990s had given the US a God-given opportunity to play a unique and timely leadership role in the development of a global system rooted in neoliberalism, supported by US military power.

The highly influential foreign policy lobby group Project for a New American Century was founded in 1997 from a conviction that the United States should play a near-messianic role, in marked contrast to the weak self-serving Clinton administration. And months after George W Bush’s inauguration and shortly before 9/11, leading neoconservative writer Charles Krauthammer claimed the US had the right to pursue unilateral policies in the wider global interest:

With neoconservative thinking dominating US foreign and security policy eight months into the Bush administration, 9/11 came as an appalling shock – and a threat to the very idea of the ‘New American Century’ just as it was getting under way. The Afghanistan war followed within weeks. It appeared initially to be a great success from the US perspective, with the Taliban quickly toppled from power, and was followed by Bush’s January 2002 State of the Union Address.

This made clear that rescuing the new century went far beyond al-Qaeda and the Taliban to take on Bush’s “axis of evil” – his term for states believed to be supporting terrorism and seeking weapons of mass destruction. As he put it to Congress, referring to North Korea, Iran and Iraq:

Pursuit of such states would be intensive. He told graduating students at West Point military academy: “…the war on terror will not be won on the defensive. We must take the battle to the enemy, disrupt his plans, and confront the worst threats before they emerge. In the world we have entered, the only path to safety is the path of action. And this nation will act.”

The pursuit, he added, would be uncompromising: “All nations that decide for aggression and terror will pay a price. We will not leave the safety of America and the peace of the planet at the mercy of a few mad terrorists and tyrants. We will lift this dark threat from our country and from the world.”

By March 2002 it was clear that Iraq would be the first target. Many countries were becoming concerned about the US taking on this military role, including France and Germany, but some leaders gave their full support, notably prime minister Tony Blair in the UK. In Washington, the question of ‘Why Iraq?’ was being answered by those involved in planning the war.

At a conference I attended in Washington just after Bush’s address to Congress, a member of the Bush transition team explained patiently to European academics what lay ahead. The coming war wasn’t really about Iraq, they said, it was about Iran, which had been seen as the main enemy in the region ever since the Iranian Revolution in 1979.

The thinking was that Iran, with a much larger population than Iraq and an entrenched anti-American religious leadership, would be much more difficult and costly to defeat. If Iraq was occupied, though, Iran would end up with a pro-US Iraq and allied Arab Gulf states to the west, a pro-Western post-Taliban Afghanistan to the east and the US Navy dominating the Arabian Sea and the Gulf. Iran would have to behave itself.

There was a saying in security circles in Washington that ‘the road to Tehran runs through Baghdad’. Get Iraq right and the Iran ‘problem’ would be sorted, many believed, with US influence across the Middle East and West Asia assured and the New American Century back on track, to the benefit of the world.

The war itself started 20 years ago this week and seemed to go Washington’s way. Troops moved rapidly from Kuwait up the Tigris and Euphrates valleys and arrived in Baghdad in less than a month. The regime collapsed and a US-led and Pentagon-managed Coalition Provisional Authority was installed to run the country along neoliberal free-market lines.

It didn’t work out that way. Saddam Hussein’s feared special forces seemed to have disappeared in defeat, but they had actually gone to ground with weapons intact and quickly helped to drive a bitter urban insurgency which, along with multi-confessional conflict across much of Iraq, drove continuing fighting. This hugely bloody and costly war lasted the rest of Bush’s presidency. It was only when Barack Obama came to power in 2008 that the White House could start to talk of Iraq being a ‘bad’ war. Even so, it lasted until 2011, by which time Obama had withdrawn most US troops.

But that was far from the real end of the war. Al-Qaeda in Iraq (AQI) had survived and by 2012 was regrouping and taking control of territory across northern Iraq and north-west into Syria. By 2014 it was seen as a threat to US and other Western interests and Obama ordered the US into a war fought almost entirely from the air with drones, missiles and strike aircraft. Over 100,000 smart bombs and missiles were used between 2014 and 2018, killing at least 60,000 people, including thousands of civilians, and eventually forcing AQI, now known as ISIS, to give up most of its territory.

The war has been immensely costly, especially for Iraqi civilians, with at least 186,000 killed directly and several times that number seriously injured, many of them maimed for life. Even now, much of Iraq remains violent, with many hundreds of civilians killed each year. ISIS remains active in both Iraq and Syria, but even more significantly, violent paramilitary Islamist groups are active in at least a dozen countries – not just in Iraq, Syria and Afghanistan.

Across the Sahel region of Sub-Saharan Africa, from Mauretania through Mali, Burkina Faso, Niger, northern Nigeria and Chad, Islamist paramilitaries are active, as they are in Somalia, the Democratic Republic of the Congo and Mozambique. Violence regularly spills over into Kenya and Uganda and there is no end in sight.

Twenty years ago, and three weeks into the Iraq War, it all seemed to be going well for the US and its coalition partners. But I wrote an openDemocracy column taking a much more negative view and predicting a long war. Titled ‘A thirty-year war’, the article seemed a bit over the top at the time, but we are now two-thirds of the way to that 30 years and there is no end in sight.