Unauthorized possession of classified military information is a serious crime.
Unfortunately, if these miscreants live in a country hostile to the United States, which would like to get its hands on American defense secrets, it's unlikely that this will help to lead to their prosecution.
Thus, there's an urgent need to make nuclear weapons obsolete, so that the United States can have something better, with which to effect regime change in Russia and China. Then our computers will be safer, because ransomware scum would have no place to hide.
While we're waiting for this to happen, though, Microsoft needs to fix Windows so that things like this just can't happen. If you want to install a disk encryption utility, that should have to happen before Windows boots up - in a special "install mode" of the operating system that you only get into if you want to, something like getting into the BIOS on startup.