Jon Stewart Has a Theory

From his Daily Show interview with Stanley McChrystal:

The Iran-Iraq war of the eighties, right - Saddam and Iran are having this war.  We're funding Saddam; we're giving him arms.  Now, the general people who learned their lessons of war with Saddam are leading this ISIS - apparently there's a lot of command and control from Saddam's generals.  We are now in many ways on the side of Iran fighting these guys - and it looks like we've just shifted the Iran-Iraq war fifty miles north-east and switched sides.

As McChrystal observed, that might be overly simplistic - for one thing, Saddam's regime was a secular one - but there's some truth to Stewart's humorous observation.