[Kozak]

We actually had an even smaller nuke, the Davie Crockett that was fired from a recoiless rifle. The firing team had to get down in a ditch as they were INSIDE the blast area!

[Uncle Bill]

Blair warns of rogue nuclear strikes - September 15, 2001

[SauronOfMordor]

We actually had an even smaller nuke, the Davie Crockett that was fired from a recoiless rifle. The firing team had to get down in a ditch as they were INSIDE the blast area

The Davey Crocket was fired from a recoiless rifle launch tube, but it did not fit inside. The warhead stuck outside like an RPG-7

Now, they DID develop an atomic artillery shell that could be fired from a 152mm (6-inch) gun, which holds the title of smallest nuke (at least the smallest one whose existance is declassified)