Overwatch

The Combine Overwatch, also known simply as Overwatch, is the general self-titled name of the Combine's military and police forces on Earth. It is used as the suffix designation of the military forces in the various sectors such as Sector 17 Overwatch for City 17, Quarantine Zone, Nova Prospekt, and other parts of the world, as well as the wasteland. The name also explicitly refers to the Combine's automated Command and Control System on Earth, often encountered in the form of the Overwatch Voice. Although primarily made for garrisoning Earth, Overwatch soldiers are hinted to be deployed throughout the Universal Union on various off-world assignments in other territories.