They are wearing the intentionally nondescript, unresearched uniforms of wherever future!Military branch you personally like to believe they met during, be it SEP itself or some sort of pre-SEP army base where Gabe was marginally higher ranking soldier.
It’s actually not as exciting as you may have anticipated. In Russia, the government takes strikeball or “Airsoft” at the competitive level pretty seriously. Since all men in Russia are obligated to a brief period of military service, and firearms are difficult to (legally) acquire (although, incidentally, it’s easier to acquire firearms here illegally than it is to legally rent a saxophone) the government likes when people take it upon themselves to simulate military operations. The team I’m with during my time here is one of the most politically powerful in the region, with official support from the Russian Ministry of Defense who give them access to training grounds used by the military, abandoned military “объекты” and in the case of some simulations, lend them a segment of a motorised brigade to help run the operation along with a few dozen tanks and armored personnel carriers. As a foreigner who’s gained esteem with this team, I will be spending this weekend camping out with them, riding tanks, shooting modern Russian military rifles, chatting with Russian soldiers and genuinely promoting cooperation between our militaries. In the near future, there is a good chance our militaries could be directly cooperating but since there is very little training for American soldiers dealing with Russian soldiers and vice versa, and given my experience, degrees, and existing connections, I’m hoping to get access to one of these jobs to better promote counter terrorism efforts between the two.
TLDR: I hang out with the Russian military sometimes so they won’t assume Americans are all as dickish as trump.