The tense new trailer for Christopher Nolan‘s star-studded Oppenheimer just debuted, showing the United States in a race against time.

“This is a national emergency,” frequent Nolan player Cillian Murphy says as J. Robert Oppenheimer, the father of the atomic bomb. “We’re in a race against the Nazis. And I know what it means if the Nazis have a bomb.”

The film, based on the Pulitzer-winning 2005 book American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer, shows Oppenheimer lobbying Matt Damon as Leslie Richard Groves Jr., a United States Army Corps of Engineers officer who directed the Manhattan Project, which gave birth to The Bomb.

“We’ve got one hope,” Oppenheimer says. “All America’s industrial might and scientific innovation connected here. A secret laboratory. Keep everyone here until it’s done.” To that end, they built a series of towns in “the middle of nowhere,” Los Alamos, New Mexico. Experts in various scientific and military disciplines are recruited and moved in with their families — otherwise, they couldn’t work ’round the clock, Murphy’s character reasons.

Some of the scientists thought the bomb would incinerate the Earth’s atmosphere, something Oppenheimer checks as a “near zero” chance.

“Near zero?” Damon’s character asks, incredulous. “What do you want from theory alone?” Oppenheimer quips.

“Zero would be nice,” Damon replies.

As the tension ratchets up, Oppenheimer pledges, “Our work here will ensure peace mankind has never seen.”

Kenneth Branagh, in a Russian accent, tells Murphy, “You are the man who gave the world the power to destroy themselves. And the world is not prepared.”

Also appearing in the clip is Robert Downey Jr. The movie also stars Gary Oldman as President Harry Truman, Emily Blunt, Rami Malek, Jack Quaid, Florence Pugh and Matthew Modine.

Oppenheimer debuts in theaters July 21.

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