4. China
Throughout the past 30 years, the Chinese military has drastically expanded in both its capacity and strength. Its military is the greatest in the world in terms of total manpower. It boasts the 2nd largest submarine fleet after the United States and the second biggest tank force after Russia. The Chinese modernization efforts have been escalated quickly as well; the country is said to be working on a number of potentially revolutionary defense technologies, such as ballistic missiles and advanced aircraft systems. The largest force in the world, the Chinese military boasts an astounding 2,333,000 active duty members.