Lockheed Martin is the world's largest defence company by arms sales. The American firm builds advanced military aircraft including the F-22 Raptor and the F-35 Lightning II, along with missiles, satellites and naval systems. Boeing and Britain's BAE Systems have historically ranked among the next-largest arms producers in the world.

SIPRI is the Stockholm International Peace Research Institute, an independent organisation in Sweden that studies armed conflict, military spending and the arms trade. It is best known for publishing annual data on the world's largest arms-producing companies and on global military expenditure, figures widely cited by governments, researchers and journalists around the world.

The largest arms manufacturers are concentrated in the United States, which dominates the global rankings, followed by Western European nations such as Britain, France and Italy, and by Russia. China also has very large defence firms, but limited transparency has historically made its companies hard to rank directly against international competitors.

China has historically been excluded or hard to place in global arms-company rankings because of limited transparency around its defence industry. Without reliable public figures on sales and revenue, organisations like SIPRI could not compare Chinese state-owned manufacturers directly with Western and Russian firms, even though China is one of the world's biggest military spenders and arms producers.

Global military spending runs into the trillions of US dollars per year and has risen over time, surpassing two trillion dollars annually in recent years. The United States accounts for the largest single share, spending more than the next several countries combined, followed by China, Russia and other major military powers.