In the movie the humour comes from the incongruity of the fantasy setting with the knowing political aside.
From Hansard: https://bit.ly/2V7BgbK
> The next war on land will be very different from the last one, in that we shall have to fight it in a different way. In reaching a decision on that matter, we must first be clear about certain rules of war. Rule 1, on page I of the book of war, is: "Do not march on Moscow". Various people have tried it, Napoleon and Hitler, and it is no good. That is the first rule. I do not know whether your Lordships will know Rule 2 of war. It is: "Do not go fighting with your land armies in China". It is a vast country, with no clearly defined objectives, and an army fighting there would be engulfed by what is known as the Ming Bing, the people's insurgents.
> The more I study the problem of future war, which I do a good deal, the more I reach the conclusion that air power and sea power will provide the main offensive punch in an unlimited nuclear war of the future. Their offensive power must be mobile. Land power will be essential as a direct "stop" on the ground, in order to protect vital territories and peoples. But the strategy of those who fight on land will be defensive, since any considerable movement will not be possible owing to the terrific destruction caused to communications by nuclear bombardment, as well as by the movement of refugees. This latter is a terrific problem, and during the ten years in which I served in Supreme Headquarters in Europe, we never could get the refugee problem seriously tackled. The sea must be exploited increasingly to give surface strategical mobility, and to provide mobile launching sites for nuclear weapons.
At which point I'm starting to feel sick in my stomach and decide to abandon reading whatever it is that I was just reading. I'm already in a bad head space thanks to COVID-19, I don't want to contemplate the realities of a world in the middle of a war in which nuclear weapons are used as actual weapons.