12. South Korea
South Korea has been left with little choice but to have a large and competent military as the neighbors North Korean are known for their aggression. With this in mind, South Korea has a 13 submarines, plenty of attack helicopters, and 624,465 active personnel serving its military. All South Korean citizens have to compulsorily serve in the military, for a minimum time of 18 months in the army, 20 months in the Navy and 22 months in the Air Force. The country boasts the 6th largest air force in the world and a big number of tanks.