Matt Damon Challenges Cillian Murphy in Intense New Trailer for 'Oppenheimer': Watch

Oppenheimer is in theaters July 21

Matt Damon is questioning Cillian Murphy's priorities in Oppenheimer.

In the newest trailer for Christopher Nolan's upcoming star-studded biographical drama, Damon, 52, plays Leslie Groves, a real-life Army engineer officer who is shown advising J. Robert Oppenheimer (Murphy, 46) to think about the potential trade-off of his effort to successfully test-detonate an atomic bomb he creates during World War II.

"Are you saying there's a chance that when we push that button, we destroy the world?" Groves asks Oppenheimer at one point.

"Chances are near zero," the latter says, which leads Groves to respond, "Near zero?"

"What do you want from theory alone?" the theoretical physicist asks.

"Zero would be nice," Groves says.

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But Oppenheimer seems to believe a small risk is worth it. "We're in a race against the Nazis ... and I know what it means if the Nazis have a bomb," he says at the beginning of the trailer.

The rest of the three-minute preview gives viewers a peek at several other cast members starring alongside Murphy and Damon, including Florence Pugh, Emily Blunt, Robert Downey Jr., Kenneth Branagh, David Krumholtz and Josh Peck.

Oppenheimer, which will premiere on July 21, is based on the Pulitzer Prize–winning biography titled American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer. Oppenheimer famously led the Manhattan Project, the effort to create an atomic bomb during World War II.

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Damon gave an interview to Variety in March on the red carpet for his recent Nike drama Air, in which he revealed that Oppenheimer has a nearly three-hour runtime.

He also rained praise upon costar Murphy — who had smaller roles in Nolan's Batman films, plus Inception and Dunkirk, and has expressed interested in playing a lead for the acclaimed director, 52.

"Cillian is everything you would want him to be. He is phenomenal. He's phenomenal," Damon raved.

And despite the movie's longer runtime, the Oscar winner added, "It goes so fast, it's great."

Oppenheimer is in theaters July 21.

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