On April 20, an Iraqi armored platoon was probing into insurgent-held territory near the city of Ramadi. Aside from a dozen MTLB armored vehicles, the Iraqi unit included at least one upgraded T-55 tank.

At least on paper, the platoon was more than enough to defeat lightly-armed insurgents. But as the column passed through the suburb of Al Humayrah—along a road flanked by high-walled compounds—the vehicles began exploding.

Insurgents with wire-guided anti-tank missiles—and professing allegiance to the hard-line Salafist group the Islamic State of Iraq and the Levant— caught the vehicles in a deadly ambush. […]