For decades, robots have been being built that are increasingly capable and lifelike, but for the most part, it’s always been easy to differentiate a robot from a person. Their clunky movements, inability to navigate varied terrain and the whirring of servos and electric motors tend to make it pretty easy to tell the difference between an early model terminator and your friend Randy that you talk “Game of Thrones” with at the water cooler.

Of course, as militaries around the world continue to work toward creating more autonomous solutions to the age-old problems of war, it’s only a matter of time before the line starts to get a bit blurry.

Like with Petman, the Boston Dynamics robot designed to test chemical and biological suits for the U.S. military. The robot actually produces a lifelike environment inside the suit, while monitoring in real time to detect any chemicals that manage to leak through it. The robot’s skin, beneath its protective suit, even sweats to ensure the suit can be tested in close to real circumstances, without risking the safety of a human being.

The result? A terrifyingly lifelike human facsimile, complete with sweaty armpits and tellingly clenched fists.

What really draws Petman into the darker reaches of the uncanny valley is your inability to rapidly discern this robot from an actual soldier fully clad in a protective suit. Although its stride is a bit unusual (getting robots to effectively walk like humans remains a significant challenge to engineers), you likely would assume this robot was an actual U.S. soldier if it approached you in the chaotic environment of a combat zone. Even the name, Petman, is a bit unnerving.

Of course, Petman wasn’t designed to go into combat, but rather to stay put in Boston and serve as a kind of crash test dummy for the worst kinds of chemical and biological weapons we humans tend to lob at one another, but robotics is a compounding technological field – meaning the advancements that make one specialized robot like Petman more lifelike are often incorporated into the next generation of multi-purpose robots intended to accurately emulate human activities.

Petman with and without suit, courtesy of Boston Dynamics/DARPA

That means, despite Petman’s current obligations, his tech could easily find its way into future incarnations of different kinds of robots, complete with refillable sweat glands and a strut that feels reminiscent of how cartoon characters would walk while playing jazz music.

To be fair, however, Petman doesn’t actually sweat, as you can see with his protective suit removed, this lifelike robot bears a stronger resemblance to Johnny Five than it does to Lt. Cmdr. Data – so perhaps the more important lesson to be derived from these videos is how soon robots will begin to blur the lines between machines and people per our perspective. If all it takes to make Petman uncomfortably convincing is a chemical suit and a gas mask, you can rest assured that data is being gathered about how best to trick the casual observer.