looks like the blokes on either end are Brits - Help for Heroes wristbands... i'd lay odds on the bandana wearing chap with the M-16 being the American. the moustache/fag combination, plus cloosing an M-16 and wearing a bandana, swings it. he's also got a couple of US issue pouches, the one that gives it away is the light grey one - its in a pattern called ACU, it was developed for the US Army in Iraq and Afghanistan at enormous expence, and was so successful that they started replacing it two years later with a pattern based on the greeny-tan looking pouch on the other side of his belt.
wild speculation says the septic has used a rifle before, but is more 'Call-of-Duty' than he is Delta Force, i reckon the two brits have some military experience from the way they hold their rifles (though i'm not sure the big bushy beard smacks of paying close attention to the local politics). not sure about the other, presumably the German...
the uniform they are all wearing looks like a commercial rip-off of the USMC's MARPAT uniform - its got more light coloured bits in it. it doesn't exactly look ideal for the environment they're in..
war geek mode off/
wouldn't read too much into the ACU camo pouch the chinese have copied it, fakes are easily available on Aliexpress.
http://www.aliexpress.com/item-img/...Trainer-Survival-war-game-ACU/1610399504.html