I can't remember where I read it and can't think how to look it up, but as I recall the military do generally submit flight plans to the FAA even for classified

I can't remember where I read it and can't think how to look it up, but as I recall the military do generally submit flight plans to the FAA even for classified experiments. They used not to, but after a few crashes changed their processes. Would appreciate confirmation or contradiction from someone who knows better.