[Petronski]

Post WW2 the US didn't have nukes, it's two were dropped on Japan.

The US had three gadgets in early July 1945: Trinity test, Hiroshima and Nagasaki. August 10, 1945 there were none left, though Oak Ridge had produced enough fuel by late November 1945 to make another Plutonium ('Fatman') device.

[Stavka2]

When I say Post, let me quantify, in the following half year. The Japanese fell for the threat of more, an empty threat, but hay, how could they have known it?