Don’t believe everything you see.

We are all aware of the ongoing battle against fake news—which frequently includes made-up text and doctored images—but a new computer program can manipulate video in a way that’s disconcertingly convincing.

The program can alter video in such a way that the person on-screen mirrors the movements and expressions of someone in a different video.

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Set to be unveiled at a computer animation festival in Vancouver, the software can also tweak head and torso poses, eye movements and background details to create more convincing fakes, according to Science News.

These video forgeries are “astonishingly realistic,” Adam Finkelstein, a computer scientist at Princeton University not involved in the work, told Science News.

The program could have practical uses, such as producing dubbed films where actors’ lip movements match a voiceover, but it could also take the problem of fake news to a whole new level.

Science News reports the algorithm starts off by scanning two different videos frame by frame, tracking 66 so-called “facial landmarks” to map someone’s features, expression, head tilt and line of sight.

For instance, in the example posted above, which shows former President Barack Obama and Russian President Vladimir Putin, the program would distort Putin’s image to adopt Obama’s head pose and facial expression.

The technology can even tweak shadows, change someone’s hair or adjust shoulder height.

The end result? A weird video of Putin doing a convincing imitation of Obama’s exact motions and expressions.