Debka Daily. 'nuff said.
In about 1960 or so I read a "War" comic (the kind my Mom did not like) about 2 or 3 American special forces types planting "mini nukes" in the USSR & PRC! And the POTUS telling the world about it (after the guys are heroically killed after completing there mission)
IMHO the reason the USSR, PRC or the USA never attempted direct planting of nukes on foreign soil was that discovery would lead directly to war at, perhaps, not the best time.
The perfection of SLBM's solved this issue.