The average American history teacher might suggest the U.S. dropped atomic bombs on the Japanese cities of Hiroshima and Nagasaki in August 1945 to end World War II. It was a controversial decision — lauded by some and called a myth by others — to sacrifice thousands in order to save millions.

And while the toll was incalculable, the cost of developing the bomb resulted in even deeper consequences for humanity, an idea explored in Christopher Nolan’s (“Dark Knight,” “Inception,” “Dunkirk”) upcoming movie “Oppenheimer.”

The trailer for the film, in 186 seconds, manages to showcase both the brilliance and seeming arrogance of J. Robert Oppenheimer (Cillian Murphy) in the race to build a devastating weapon to compete with Axis forces.

“Our work here will ensure a peace mankind has never seen,” Oppenheimer says in the trailer.

But, as history tells us, the creation of the bomb did not bring about complete peace, and the arms race and Cold War that followed have continued to radiate global repercussions ever since.

As the countdown to the first atomic bomb test rolls in the background of the trailer, an unnamed character played by Kenneth Branagh gravely professes, “You are the man who gave them the power to destroy themselves, and the world is not prepared.”

“Oppenheimer” hits theaters on July 21.

Originally published by Military Times, our sister publication.