The US military-industrial complex is the single largest institutional hydrocarbon consumer and greenhouse gas emitter on the planet. It would be pretty stupid for me to listen to the government's advice about how best we should preserve the environment.
China has been the largest ghg emitter for the last 20 years, and currently emits more than twice as much as the us. Gdp spent on defense is similar as a fraction of gdp (slightly more in the us). So realistically the Chinese military is by far a larger emitter of ghg than the us military.