Because the government knows IR would be a pivotal tool in a civilian guerrilla uprising, and they want to keep such things out of the hands of the proletariat?

Got it. It was a genuine question asked out of ignorance on my part.

How would the extra resolution be useful in warfare?

Anti aircraft missiles (everything from plane launched to manpads), heat seeking weaponry capabilities, night vision, multispectrum sensors, optical gas imaging and a whole host of other dual use scientific applications. High resolution thermal vision is the lynchpin behind all of them. I am not sure why they are still tightly controlled since you can easily acquire them overseas.

The US government is terrified of its citizenry, as they are the only people that stand a chance of “fixing” it.