OK, so the robot apocalypse probably won't happen any time soon, but the new robot sentries guarding Microsoft's Silicon Valley campus seem like something straight out of a futuristic sci-fi movie.

According to ExtremeTech, each of the K5 security guard robots from robotics company Knightscope stands 5 feet tall and weighs 300 pounds, so you probably don't want to mess with one.

The K5 robots don't come with any weapons onboard--thankfully--but they use a suite of alarms, sirens, and cameras to monitor and patrol the grounds of Microsoft's campus. If one spots trouble, it'll either sound an alarm or dispatch a human security guard to its location. 

ExtremeTech notes that the K5 can run for up to 24 hours on a single charge, and can recharge in only about 20 minutes. Its battery won't die out in the field, though--these bots will return to the charging station by themselves when their batteries start to run dry.

The story behind the story: Robots are playing an increasingly large role in security and military operations. Google-owned robotics company Boston Dynamics, for example, has been working with DARPA to develop various robots to aid soldiers in combat settings. Meanwhile, South Korea deployed a robotic sentry to guard its side of the Demilitarized Zone  in 2010. Unlike K5, though, South Korea's guard robot came fully armed.