In a conversation with John Kelly, Trump asked him why our Generals couldn't be like "The German Generals of WWII"

I think he means being willing to invade another country based solely on fascist ideology to destroy an out-group (given it's the US, this would likely refer to either Muslims or those from Latin America) in a war of extermination. In the German Generals' case, that would be the Judeo-Bolshevist state of the USSR which was in the view of the Nazis somehow both communist and run by rich Jewish bankers simultaneously.