Surprising no one who paid attention, the reason why Iraqis didn’t want a residual U.S. presence is because many of them view their American occupiers as murderers. The Post thinks this is a story about the past. But the real story is about how that anger is Iran’s biggest opportunity come December 31.

I’m a broken record on this, but it’s important so I continue. Starting on January 1, the U.S. presence in Iraq that will be the most resonant to Iraqis comes from the hired guns of the State Department. Around 5,000-5,500 mercs will guarantee the safety of diplomats in their compounds and as they move between them. No one outside State, including the Special Inspector General for Iraq Reconstruction, knows the basic rules of engagement for how they’ll operate. Add two other contextual facts: the State Department has no experience managing a military structure the size of a heavy combat brigade; and it’s putting one together on the fly.

It is not the job of mercenaries to care about the U.S. reputation in Iraq. It is not the job of mercenaries to care about broad U.S. goals in Iraq. It is their job to keep Iraqis from harming diplomats. Step back or they shoot.

If you’re Iran, you want to make sure they shoot. It’s the most obvious play, the most foreseeable disaster. Use your operatives to put some souped-up IEDs on the roads. Have your proxies spray up SUVs with diplomatic plates. Or just have them drive too close to the convoys.

As soon as the mercs open fire, it’s gasoline on the flame of Iraqi resentment toward their former occupiers. Every other goal the U.S. has in Iraq — keeping Maliki from becoming a new strongman; keeping Maliki from defaulting to Iranian foreign policy goals; whatever — gets whited out by the noise. Whatever diplomatic influence the U.S. has, whatever leverage it possesses — it shrinks. Iraqi politicians who want stuff exploit the incident and raise the price of their cooperation with Washington. And on and on and on.

The diplomats in Iraq are a target on January 1. They’re trying to outsmart the Iranians. But the best opportunities the Iranians have are wearing wraparound shades, goatees and corny-ass tribal tattoos, and they’re yelling at Iraqis to step the fuck back.