Well, in short I hate you. This was really quite enthralling, and I wish I could write something along these lines. It's very well written, you had great foreshadowing I thought, by mentioning Jimmy at least a few times throughout the story. The big reveal at the end to me was expected but also nicely done. I loved the whole 'dead head" thing being a neurotic of sorts. Your dialogue flowed easily, and fit the characters nicely. I loved the whole laughing during combat thing, that kind of sick stuff makes a story more real for me. I could definitely feel the tension through Escobar and the rest of the team. I'm not sure if this is a first chapter of a novel or a short story, but it easily works as both, especially short story.
One thing did bother me however - there was a point in the story where Escobar is searching for mines and finds the grenades, and he says "just as I thought" and then again right after it at a different spot, it pulled me out a little bit because thinking "just as I thought" seemed a redundant thing to say in that situation, and there wasnt any previous statements that solidified what escobar said other than that one line. If that makes sense? I couldnt find any foreshadowing in that thought line, it just seemed to show up to me. I'd try adding a bit of thought foreshadowing before that, or using a different line, it could work I guess for the second time, but I just didnt feel like Escobar would say that in his head.
Overall - fantastic job, I seriously loved the story.