I remember reading, in the late 1960s that the USSR had firearms stashes hidden in the US for when a war broke out.
None were ever found but ever so often I read of such a stash being found in France from the early 1940s.
Reminds me of the movie TELEFON(1977)
That we were allowed to know about.
There were many lunatic projects planned by the Russians (and by the US) which were fortunately cancelled by their sponsors before getting underway.
If there were caches of small arms intended for US terrorist groups in the 60's and 70's those have probably all been found and "properly disposed" by now.