377 Tons of Explosives...

Are missing from stockpiles in Iraq. Now, a ton isn't a measurement that I'm familiar with, so, in case you didn't know, a ton is about 2,000 pounds. And 2,000 times 377 = 754,000 pounds of explosives are missing in chaotic and insecure Iraq, possibly fueling an endless amount of car bombs.
I am no genius here, but this robbery would take a lot of manpower. For instance, the Daily Kos reports that an average freight container, "can carry ~46,100 pounds when loaded and packed appropriately, riding on roads that are rated for such loads (bridges, tunnels, and roadway that can handle such loads without collapsing...that means no dirt roads, no bad bridges, etc)." In essence, twenty freight trucks would be needed to carry out this operation, if conditions permitted.
Now, we know that the insurgents don't have a bunch of freight trucks handy, so let's be a little more realistic. What if, now just play along with me here, they had a bunch of 2004 Toyota Tundras at hand. The max payload for the truck, according to Vehix, is 1,710 pounds or slightly less than a ton. Altogether, they would need about 440 Tundras to make this happen.
And mind you this is Iraq, where we already have thousands of troops and thankfully only conventional explosives. Imagine some of the former Soviet countries where nuclear materials are just floating around without any sort of security. If people there became as organized as Iraqi insurgents... wow... this could get really really bad.