In 2007, China sent a ballistic missile arcing into space on a collision course with one of its own defunct satellites, destroying its orbital target. The U.S. responded in kind the following year, using a ship-based missile to knock one of its own malfunctioning satellites out of the sky.
The Pentagon colored its anti-satellite mission as a means to disperse the satellite's supply of toxic propellant before it de-orbited and crashed to Earth, and while that might be partially true, the launch also provided important radar and targeting data that will help the DoD monitor (and potentially target) space objects in the future. It also sent a strong message. Both exercises were demonstrations of military capabilities that reach into space, where a new game of strategic and technological one-upmanship is just beginning to unfold.