In his new book, “Dark Forces: The Truth About What Happened in Ben­ghazi” (Broadside Books), writer Kenneth R. Timmerman explains how the US government’s efforts to arm the Libyan rebels backfired, flooding weapons into Syria, and as he ­reveals here, Afghanistan:

The Obama administration isn’t only giving the Taliban back its commanders — it’s giving them weapons.

Miliary records and sources reveal that on July 25, 2012, Taliban fighters in Kunar province successfully targeted a US Army CH-47 helicopter with a new generation Stinger missile.

They thought they had a surefire kill. But instead of bursting into flames, the Chinook just disappeared into the darkness as the American pilot recovered control of the aircraft and brought it to the ground in a hard landing.

The assault team jumped out the open doors and ran clear in case it exploded. Less than 30 seconds later, the Taliban gunner and his comrade erupted into flames as an American gunship overhead locked onto their position and opened fire.

The next day, an explosive ordnance disposal team arrived to pick through the wreckage and found unexploded pieces of a missile casing that could only belong to a Stinger missile.

Lodged in the right nacelle, they found one fragment that contained an entire serial number.

The investigation took time. Arms were twisted, noses put out of joint. But when the results came back, they were stunning: The Stinger tracked back to a lot that had been signed out by the CIA recently, not during the anti-Soviet ­jihad.

Reports of the Stinger reached the highest echelons of the US command in Afghanistan and became a source of intense speculation, but no action.

Everyone knew the war was winding down. Revealing that the Taliban had US-made Stingers risked demoralizing coalition troops. Because there were no coalition casualties, government officials made no public announcement of the attack.

My sources in the US Special Operations community believe the Stinger fired against the Chinook was part of the same lot the CIA turned over to the ­Qataris in early 2011, weapons Hillary Rodham Clinton’s State Department intended for anti-Khadafy forces in Libya.

They believe the Qataris delivered between 50 and 60 of those same Stingers to the Taliban in early 2012, and an additional 200 SA-24 Igla-S surface-to-air missiles.

Qatar now is expected to hold five Taliban commanders released from Guantanamo for a year before allowing them to go to Afghanistan.

But if we can’t trust the Qataris not to give our weapons to the Taliban, how can we trust them with this?