What if the general says 'no' to president's nuclear order?

What if the general says 'no' to president's nuclear order?  ABC News No one can prevent Trump from using nuclear weapons, experts say  USA TODAY General heading Strategic Command says illegal nuclear launch order can be refused  NBCNews.com Concern over Trump's access to nukes spikes  The San Diego Union-Tribune Top general says he would resist "illegal" nuke order from Trump  CBS NewsFull coverage