@Gary_Totty (et al) The US 155mm nuke round was better than that. According to Wikipedia, the W48 warhead had a range of around 8-10 miles and a yield of .072kt.
The really small, and perhaps suicidal weapon was the Davy Crockett. This was a recoilless rifle that fired a W54 warhead, with a yield of 20 tonnes TNT. It had a range of 1-2.5 miles (less than a modern tank) and was recommended to fire over a hill to provide some protection for the firing crew. I would shoot the 155mm, but not the Davy Crockett.
Ken