From the moment the US began sending lethal arms to Syrian rebel factions, there were a chorus of people expressing fears that those arms would end up in the “wrong hands,” and US officials insisted they were going to carefully vet everyone who got those weapons.

You know who got a lot of those weapons? ISIS. Just as everyone predicted would happen, once the arms were smuggled into Syria, they quickly ended up spread out among rebel factions, both pro-US and not, and a new report shows massive amounts of ISIS armament was actually stamped “Property of US Govt.”

Some of those small arms were surely looted from Iraqi bases during the offensive in Mosul, which is also where ISIS got most of its arsenal of US-made military vehicles. That’s not the whole story, however.

The ISIS weapons, cataloged after being captured by Kurdish forces, also included US-made anti-tank missiles that appear to have been part of a delivery provided to the Free Syrian Army (FSA), one of those carefully vetted rebel factions.

How the TOW missiles got from FSA “moderates” to ISIS is anyone’s guess, but the factions are not so starkly divided as officials have imagined, and fighters and gear often flow back and forth.

Pinning down the exact route the US arms took to get to ISIS will be all but impossible, as ISIS appears to have had the foresight to weld over the serial numbers to prevent any conclusive proof of the chain of transactions.

The Syrian rebel factions still getting US arms loudly denied that they were providing their arms to ISIS, and insisted the “overwhelming majority” of US military aid is still being used by the FSA to fight America’s enemies.

That’s a fiction ISIS seems only too willing to continue facilitating, as it would keep those massive US arms shipments flowing, giving ISIS a convenient source of arms as the US air war continues to boost its recruitment numbers.