The advocates of forever wars will never admit it, but the Biden administration’s decision to withdraw all troops from Afghanistan by the 20th anniversary of 9/11 — and the consequent decision by other nations like Australia to do the same — will bring to an end a war that made the West less safe against terrorism and corroded Western military forces for an extraordinary cost that will continue to be paid for decades to come.

Along with Iraq, Afghanistan stands as one of the greatest policy failures of recent decades, with a horrific human and economic toll. This is all a result of the hysterical abandonment of reason in the wake of 9/11 by Western leaders like George W. Bush, John Howard and Tony Blair — and what they believed were the political benefits of embracing militarism.

First, the cost: 41 Australian soldiers killed and 261 Australia Defence Force personnel injured. A total financial cost of, by one estimate, $10 billion. The cost for the United States is 2218 deaths within Afghanistan and nearly 20,100 casualties. The financial cost has been just under US$1 trillion. A 2016 estimate suggested that there had been 173,000 people killed and more than 183,000 seriously wounded in Afghanistan and Pakistan.

Those are only the direct costs. The cost of treating permanently incapacitated veterans of the conflict will continue for decades to come. And, along with the Iraq conflict, the war has inflicted a grisly toll on veterans’ mental health. There have been at least 500 suicides of veterans since the beginning of the Afghanistan conflict, according to the ABC. The rate of veteran suicide is so concerning that the government is under sustained and mounting pressure to call a royal commission.

In the United States, more than 6000 veterans take their own lives every year — or more than 17 a day — and the number has risen since 2016.

The war badly corroded the military institutions tasked with fighting it. The “Afghanistan Papers” published by the Washington Post in 2019 revealed that the US military, along with civilian political leaders, persistently lied to Americans about the state of the war and the prospects for success. Data was doctored or spun from the conflict, while the US military was, in the words of one three-star general, “devoid of a fundamental understanding of Afghanistan — we didn’t know what we were doing…. We didn’t have the foggiest notion of what we were undertaking.”

For Australian forces, the corrosion was far worse. The Brereton report revealed “credible information” of war crimes committed by 25 Australian soldiers involving the deaths of 39 Afghans, widespread breaches of laws and customs of war, systemic coverups and a deeply toxic culture within the SAS.

With the Taliban poised to return to power, the security gains from the conflict appear limited at best. It is more likely that the Afghanistan conflict, along with the Iraq War, has — in a view now so mainstream intelligence agency heads have long been happy to espouse it — encouraged radicalisation both in the West and in Muslim countries, and served to confirm the narrative offered by Islamist terrorists like Islamic State about Western aggression against Muslims.

To use the words of one Pentagon report in 2004, “the dramatic narrative since 9/11 has essentially borne out the entire radical Islamist bill of particulars. American actions and the flow of events have elevated the authority of the Jihadi insurgents and tended to ratify their legitimacy among Muslims.”

The US use of drone aircraft to carry out targeted — and frequently, entirely untargeted — airstrikes also played its role. As Stanley McChrystal, the general behind the US counterinsurgency plan in Afghanistan, explained in 2013: “the resentment created by American use of unmanned strikes … is much greater than the average American appreciates. They are hated on a visceral level, even by people who’ve never seen one or seen the effects of one.”

But the fact that we are no safer from Islamist terrorism now than in 2001 — our threat level officially remains at “probable” — isn’t the only issue in regard to the impact of the forever wars on our security. It’s now clear that white supremacist terrorist groups in the United States — which have for several years now been formally regarded as a greater threat to US domestic security than al-Qaeda or other Islamist terrorists — seek to draw on Afghanistan and Iraq veterans and serving military personnel. A 2019 survey showed that more than a third of US military personnel respondents had encountered white supremacist or racist ideology within their ranks.

The recruitment of military veterans obviously brings military expertise to terrorist groups but, in the words of one Pentagon official, it “also brings legitimacy, in their minds, to their cause — the fact that they can say they have former military personnel that align with their extremist and violent extremist views”.

Yet national security commentators continue to insist Western military forces should remain in Afghanistan and that the US withdrawal — a delayed implementation of the agreement Donald Trump, in one of his few sensible moments, negotiated with the Taliban — will be a disaster.

“By forcing the Americans to leave and seizing Kabul, the Taliban would inspire jihadist groups elsewhere to escalate their terror campaigns… the Taliban wielding absolute power in Afghanistan would pose a greater jihadist threat to the free world than any other group, including al-Qaeda or Islamic State remnants,” wrote one just this week (it was run by Australia’s own house of neocon militarism, ASPI).

As one Biden administration official has pointed out, waiting for the right moment to leave Afghanistan will mean the West never leaves — and can never start the process of addressing the enormous, and continuing, costs of a war both epically long and an epic failure.