I’m not sure where the idea that this took a shit-ton of planning came from. Basically, a bunch of people assaulted two places that were known to be where the American diplomatic corp worked out of.

At first, we thought it was just a mob, but then it became clear that they were experienced attackers. That doesn’t mean that they didn’t quickly decide to do this. It wasn’t D-Day. They came with a lot of guys and a lot of weapons and launched a vicious assault.