The terrorist takeover of Afghanistan, following President Joe Biden’s precipitous and bungling military exit, has brought an ignoble end to America’s longest war. This is a watershed moment that will be remembered for formalising the end of the long-fraying Pax Americana and bringing down the curtain on the West’s long ascendancy.

At a time when its global pre-eminence was already being severely challenged by China, the United States may never recover from the blow this strategic and humanitarian disaster delivers to its international credibility and standing. The message it delivers to US allies is that they count on America’s support when they most need it at their own peril.

After all, the Afghanistan catastrophe unfolded after the US threw its ally – the Afghan government – under the bus and got into bed with the world’s deadliest terrorists, the Taliban. President Donald Trump first struck a Faustian bargain with them, and then the Biden administration rushed to execute the military exit dictated by the deal, even though the Taliban had been openly violating the agreement.

The dramatic collapse of the Afghan defenses and then the government was directly linked to the US betrayal. Biden admits Trump “drew US forces down to a bare minimum of 2,500” in Afghanistan. By refusing to retain that small military footprint and by ordering a rapid exit at the onset of the annual fighting season, Biden pulled the rug out from under the Afghan military’s feet, thus facilitating the Taliban’s sweep.

The US had trained and equipped the Afghan forces not to play an independent role but to rely on American and NATO capabilities for a host of battlefield imperatives – from close air support, including drones for situational awareness, to keeping US-supplied weapon systems operational. Biden’s calamitous troop pullout without a transition plan to sustain the Afghans’ combat capabilities unleashed a domino effect, with 8,500 NATO forces and some 18,000 US military contractors also withdrawing and leaving the Afghan military in the lurch.

As former CIA Director General David Petraeus has explained, ever since US combat operations in Afghanistan ended on January 1, 2015, Afghan soldiers had been bravely “fighting and dying for their country” until the US suddenly ditched them this summer, mortally compromising Afghan defenses. This assessment is reinforced by the number of military deaths: Since the US combat role ended more than six and a half years ago, Afghan security forces lost tens of thousands of soldiers, while the Americans suffered just 99 fatalities, many in non-hostile incidents.

This is not the first time the US has dumped its allies – or even the first time in recent memory. In the fall of 2019, the US abruptly abandoned its Kurdish allies in northern Syria, leaving them at the mercy of a Turkish offensive.

But in Afghanistan, the US sowed the wind and reaped the whirlwind. Its self-inflicted defeat and humiliation have resulted from a failure of political, not military, leadership. Biden, ignoring conditions on the ground, overruled his top military generals in April and ordered all US troops to return home. Now, two decades of American war in Afghanistan have culminated with the enemy riding triumphantly back to power.

Whereas 58,220 Americans (largely draftees) were killed in Vietnam, 2,448 US soldiers (all volunteers) died over the course of 20 years in Afghanistan. Yet, the geopolitical implications of the US defeat in Afghanistan are much more significant globally than the American defeat in Vietnam.

The Pakistan-reared Taliban may not have a global mission, but their militaristic theology of violent Islamism makes them a critical link in an international jihadist movement that whips hostility toward non-Sunni Muslims into nihilistic rage against modernity. The Taliban’s recapture of power will energise and embolden other violent groups in this movement, helping to deliver the rebirth of global terror.

In the Taliban’s emirate, al-Qaeda, remnants of the Islamic State (ISIS), and Pakistani terrorist groups are all likely to find sanctuary. According to a recent United Nations Security Council report, “the Taliban and al-Qaeda remain closely aligned” and cooperate through the Pakistan-based Haqqani Network, a front for Pakistani intelligence.

The unravelling of the effort to build a democratic, secular Afghanistan will pose a far greater threat to the free world than Syria’s meltdown, which triggered a huge flow of refugees to Europe and allowed ISIS to declare a caliphate and extend it into Iraq. The Taliban’s absolute power in Afghanistan will sooner or later threaten US security interests at home and abroad.

By contrast, China’s interests will be aided by the Taliban’s defeat of the world’s most powerful military. The exit of a vanquished America creates greater space for China’s coercion and expansionism, including against Taiwan, while underscoring the irreversible decline of US power.

An opportunistic China is certain to exploit the new opening to make strategic inroads into mineral-rich Afghanistan and deepen its penetration of Pakistan, Iran, and Central Asia. To co-opt the Taliban, with which it has maintained long-standing ties, China has already dangled the prospect of providing the two things the militia needs to govern Afghanistan: diplomatic recognition and much-needed infrastructure and economic assistance.

The reconstitution of a medieval, ultra-conservative, jihad-extolling emirate in Afghanistan will be a monument to US perfidy. And the images of Chinook and Black Hawk helicopters transporting Americans from the US embassy compound in Kabul, recalling the frenzied evacuation from Saigon in 1975, will serve as a testament to America’s loss of credibility – and the world’s loss of Pax Americana.