What usual suspects? Since when does US or its allies produce Toyota Landcruisers. ISIS got its weapons from the sales made by the US, Russia and others to the Iraqi army. Slack controls over military stockpiles and endemic corruption by successive Iraqi governments allowed ISIS to arm itself. When the US invaded in 2003 the Iraqi army disintegrated and the Sunnis at its head were hardly interested in auditing or securing the army's weapons.
So yes you can trace some of the weapons back to the US but it was not intentional. The UK armed Finnish forces fighting the Soviets at the start fo World War II. It does not mean they intended for those weapons to aid Nazi Germany as they did later.
