There is this tv series in Amazon about Einstein life and you could see him opposing using his knowledge to improve weapons, while Haber(creator of Bosh Haber process) did not.
Haber was probably murdered while traveling by secret services in the same way the US killed engineers of Iran nuclear program openly. His wife and son committed suicide because of his work.
As a technical person with decades of experience in science you can do enormous harm if you really want. All you really need is a powerful reason for that.
If you see other countries developing so strong weapons they could invade your country with no cost for them, this is a powerful reason for you to collaborate.
The US has focused so much in developing force that is seen more and more in the world as the bully while countries like China build bridges, ports or roads.