With 2.3 million active troops, the People's Liberation Army (PLA) is the largest standing military force in the world, commanded by the Central Military Commission (CMC). China has the second-biggest military reserve force, only behind North Korea. The PLA consists of the Ground Force (PLAGF), the Navy (PLAN), the Air Force (PLAAF), and the People's Liberation Army Rocket Force (PLARF). According to the Chinese government, China's military budget for 2017 totalled US$151.5 billion, constituting the world's second-largest military budget, although the military expenditures-GDP ratio with 1.3% of GDP is below world average. However, many authorities – including SIPRI and the U.S. Office of the Secretary of Defense – argue that China does not report its real level of military spending, which is allegedly much higher than the official budget.