As of May 2025, China had the largest armed forces in the world by active duty military personnel, with about two million active soldiers. India, the United States, North Korea, and Russia rounded out the top five largest armies. Difference between active and reserve personnel Active personnel, also known as active duty in the United States and active service in the United Kingdom, are those individuals whose full-time occupation is being part of a military force. Active duty contrasts with a military’s reserve force, which are individuals who have both a military role and a civilian career. The number of active duty forces in the U.S. is much larger than its reserve membership. What is the strongest army? The strength of a country’s armed forces is not only determined by how many personnel they maintain, but also the number and quality of their military equipment. For example, looking only at personnel does not factor in the overwhelmingly higher number of nuclear warheads owned by Russia and the United States compared to other countries. One way to answer this question is to look at the total amount of money each country spends on their military, as spending includes both personnel and technology. In terms of countries with the highest military spending, the United States leads the world with an annual budget almost three times larger than second-placed China.