The US Military is largely believed to be the most powerful military in the world. The next three top militaries (Russia, China, and India) all have more active duty personnel than the US Army. Russia and China also have more tanks than the United States, though China's difference is relatively small. The United States, by contrast, has substantially more aircraft and aircraft carriers than every other nation. It is second to North Korea in submarines, though not by much.
These raw numbers also obscure technological advancement in weapons systems. This is an area that the United States leads in, largely because of the US Military budget, which is larger than the combined budgets of the militaries ranked 2–19. The US Military spends a significant amount of money on research and development in addition to purchasing and maintaining equipment.