As President Donald Trump and Elon Musk argued on social media on Thursday, the world's richest man threatened to decommission a space capsule used to take astronauts and supplies to the International Space Station.

NASA entrusts SpaceX with the lives of its astronauts, and the Pentagon relies heavily on the company to launch its most sensitive satellites.

Elon Musk says that he's cutting off NASA's access to space, in a potentially devastating blow to the United States' space program.