It's been said that their Iraqi bodyguards acted nervous and then didn't turn up. So they had inside information the Americans were being targeted. The Americans were frightened, but evidently didn't make it to an embassy or American troops in time. And yes, they should have a GPS chip implanted before they ever take a job overseas.
Uhm...I hate to be stupid here...but has anyone thought of locating those nervous bodyguards that didn't show up and finding out exactly WHY they were nervous...WHO was putting the pressure on them...and WHERE THOSE PEOPLE ARE RIGHT NOW?!