They will probably be forced to. The UK is a trusted partner with US Defence firms, and are trusted with a lot of secret US tech that the US Government doesn’t want just any old country to be privy to. This special arrangement would not necessarily be inherited by an independent Scotland (especially a stridently, anti-nuclear, leftist one) and in order to maintain these arrangements with US defence contractors, BAe Systems et all will have to relocate their facilities down south or across the sea into the rUK. Would be good news for England’s defence industry, especially in Portsmouth, thats for sure.
and England cannot just hand over missiles, aircraft and ships to Scotland. There are many foreign parts on them and they need to be licensed from the home country for that.