I seriously doubt that outsiders posing as NG could infiltrate this setup. There are surely multiple layers of protection against that, including coded digital IDs or facial recognition and such.
A much bigger worry, supposedly also being dealt with, hopefully effectively, is infiltration from within, by actual NG troops who’ve been recruited by these groups and could potentially go rogue and do something.
I guess we’ll find out soon enough. 26 hours and 22 minutes to go.