“Don’t we have artillery that will fire small atomic weapons??”
There was one (155mm, `Long Tom’?) on a hill off Ft. Riley Blvd on the way from Manhattan, KS to Ft. Riley, or vice versa, many years ago.
And now for something completely different—the Army issued a nuclear hand grenade for a while, but with that blast radius there was a Silver Star pre-wired to the pin.
https://en.m.wikipedia.org/wiki/Davy_Crockett_(nuclear_device)
I believe you’re thinking of the Davy Crockett which was a warhead launched from a recoilless rifle.
There isn’t a nuclear warhead hand grenade sized.