Did you know American soldiers are taught a variation of martial arts? According to Wikipedia the muscle memory our troops learn to utilize in point shooting is similar to the way ancient warriors weilded a sword. During WWII, US and Canadian special forces were taught Jujutsu and studied the book Kill or Get Killed, by Colonel Rex Applegate. And it goes on and on. So it seems martial arts has never really gone away when it comes to warfare.
Krav Maga and Sambo are both a military, combat martial arts. Krav Maga is Israeli military based martial art to defend against guns and knives -- street warfare.
Sambo originated from the former Soviet Union and is very combative.
It's not just military personnel who benefit from MMA. My trainer helps to train local police. That way, they're ready for anything! The conditioning alone will make a person strong and the actual fighting techniques will protect them.
What's interesting is that Allied troops occupied in Japan after the end of WWII banned all martial arts activities there. The ban was lifted shortly thereafter when US servicemen showed an interest in learning them! Many of the first karate instructors in this country were actually US military personnel who trained at bases in Okinawa.
The U.S. Army trains in a hand to hand style of combat that uses Brazilian Jiu-Jitsu as a foundation called Army Combatives. Similarly, the Marines train in MCMAP, also a martial arts system. While these continue to be very effective battle field arts, they're also very useful for fostering resolve and a warrior spirit in the soldiers.