Militaries contribute a fair bit, I don't know the percentage, of CO2 produced by humans. Military jets consume a lot of fuel, though there are a lot more civilian airliners of course. Most Navy ships burn oil. Then there is the energy that goes into making weapons, and explosives. Good question.
The more I look for any kind of plan and find silly editorials that we need to burn less oil/coal the more I'm convinced we're going to run this experiment, there won't be any substantive reductions in CO2, or even leveling of it, globally, for a long time.