I don't believe he would launch nukes against someone. I don't believe that his staff would necessarily stop him, either. As far as I know nobody would be legally allowed to stop him. Even more so in the case of small scale military actions, like drone strikes or the bin Laden raid. Declarations of war are overrated.

Trump's thin skin is a proven fact. He still isn't over the jokes over his small hands. He felt the need to defend his penis size in a presidential campaign. He attacks voters at his own events. He verbally insulted almost all minority groups. His default reaction to any criticism is to personally insult the critic.