The US has spent billions supplying the Afghan military with the tools to defeat the Taliban, but the rapid capitulation of the armed forces means that weaponry is now fuelling the insurgents' astonishing battlefield successes.
"We provided our Afghan partners with all the tools – let me emphasise: all the tools," US President Joe Biden said when defending his decision to withdraw American forces and leave the fight to Afghans.
But the Afghan defence forces have shown little appetite for that fight and, in their tens of thousands, have been laying down their arms, only for the Taliban to immediately pick them up.
The Taliban's social media is awash with videos of Taliban fighters seizing weapons caches – the majority supplied by western powers.
Footage of Afghan soldiers surrendering in the northern city of Kunduz shows army vehicles loaded with heavy weapons and mounted with artillery guns safely in the hands of the insurgent rank and file.
In the western city of Farah, fighters patrolled in a car marked with an eagle swooping on a snake – the official insignia of the country's intelligence service.
While US forces took the "sophisticated" equipment with them when they withdrew, the Taliban blitz has handed the group "vehicles, Humvees, small arms and light weapons, as well as ammunition", Justine Fleischner of weapons-tracking group Conflict Armament Research, told AFP.
Experts say such hauls, on top of unacknowledged support from regional allies such as Pakistan, has given the Taliban a massive boost.
The weapons will not only help the Taliban's march on Kabul but "strengthen its authority" in the cities it has captured, said Raffaello Pantucci, senior fellow at the S Rajaratnam School of International Studies.
With US troops all but gone, the Taliban now find themselves flush with American-supplied equipment, without having to raise a single penny.
"It is incredibly serious. It is clearly going to be a massive boon to them," Mr Pantucci said.
Washington had prepared for the Taliban to claim its weapons, but the rapid fall of cities was its most dire scenario, Jason Amerine, who led US special forces in overthrowing the Taliban in 2001, told AFP.
"The US equipped the ANA with the assumption that weapons and materiel might fall into Taliban hands," he said, referring to the Afghan National Army.
"The current crisis was a worst-case scenario considered when making procurement decisions."
One of the videos flaunting the Taliban's gains showed a fighter on a red motorbike staring at a military helicopter sitting on the tarmac in Kunduz.
But without pilots, the Taliban will see no benefit on the battlefield from captured aircraft.
"They will be for propaganda purposes only," said former CIA counter-terrorism analyst Aki Peritz.
More useful will be the light arms and vehicles used to navigate the country's rugged terrain.
Coupled with the army's dwindling morale, the gains will boost the threat the Taliban pose to the western-backed government.
As the crisis unfolds, the Biden administration says it will still equip an Afghan military that appears on the verge of collapse.
Observers of the Middle East have seen this transfer of arms play out before.
After the US withdrawal from Iraq, ISIS overran the Iraqi city of Mosul in mid-2014, seizing US-supplied guns and Humvees.
The militants used their gains to build an Iraqi-Syrian caliphate the size of Belgium.
Like ISIS fighters in Mosul, joyous Taliban recruits are now posing for pictures with enemy munitions in the newly won cities in all corners of the country.
"This retreat is turning into a rout," Mr Peritz said.
