Ok I just bought the fighter planes but I am out of spending space now. You could sell them to Lithuanian SSR, as that is the country that is at war and it still should have a lot of spending space left. I figured out a genius way to transfer weapons to my other countries without worrying about the other country's spending space: stash them in my space center and just transport them to the Lithuanian SSR by cargo shuttle. That way, I get around the spending space rule that normally limits how much you can transfer :D