It's... a battle robot of sorts from an old Super Nintendo game called Front Mission: Gun Hazard. Just an awesome game that I like a lot.
(It's totally not a subliminal message to have you include battle robots in this comic which would be gigantic Soviet-made machines with the sickle&hammer emblem on the chest that would hold huge Kalashnikovs that shoot laser beams. Totally not.)
Another post, right on time! All I can say here is that there are some super intense facial expressions (except for panel two, looks like he's tired of shooting women). All that is certain is that some serious face-off is about to go down.
Thanks--expressions are something I'm always worried about, since they're so important.
(It's a real possibility. Or he's tired of fighting insurgencies, or shooting at people he sees as just kids, or not having his regular team that he's used to there, or shooting people period, or some combination of those. But I'm not a reader, and it's up to readers to decide these things. :P )