[El Gato]

Minor point ... Russia (Stalin) was on the Allied side at the time.

Only as a matter of convenience and "enemy of my enemy". If Stalin had the bomb at the end of WW-II, and we didn't', WW-III would have commenced very shortly thereafter. The world would have been a very different place than it is today.

[jamaksin]

Lest we all forget ... the US shipped to the USSR in the Spring of 1943, via the Lend-Lease program, tens of tons of nuclear materials - including enriched uranium.

Note - the Trinity Test was over a year ago at that time.