https://collider.com/robert-downey-jr-oppenheimer/
...Strauss was by no means a warmongering political hawk hungry to use the bomb, and was known for championing the peaceful use of atomic energy and how it could eventually become a widely used replacement energy source alternative to electricity. His presence in the film (and Downey's portrayal) will likely reflect the cautious optimism that Strauss had about the destructive power of what J. Robert Oppenheimer was in the process of creating. It wasn't until after the Soviet Union tested its first atomic bomb in 1949 that Strauss began a campaign for the development of thermonuclear weapons as a response. Oppenheimer was actually an outspoken opponent of Strauss' desires to harness the atom and eventually weaponize it.