It seems there is a lot of good advise coming to you from the members, so I hope it helps you.

I would like to add that objects can also trigger, as well as the news stations, and movies about servicemen or war. It would be a good idea to keep anything connected to his service, like uniforms etc. Well out of visual line.

He needs to relax and feel safe. Try keeping service colors out of the bedroom. This also may help him to relax in his new surroundings.

Hope my thoughts help.

Wish you both much happiness!

Colors