The Russians developed nuclear weapons because they didn't have a choice given the US had already done so, and it's not clear when they would have been successful without the US project.
The reason I picked the early 1960s for peacetime development is nuclear weapons development became much easier with the introduction of nuclear power. At that point it became much easier for any motivated government, so it's not surprising the South Africans were able to do it in the '70s. And still they needed US help to do it on that timeline.
I.e. that untold amounts of capital was spent on making equipment that was just sent overseas to get blown up, if the US wasn't in the war it's not like it wouldn't have had a giant export market, and all that workforce could still be mobilized to manufacture goods, except some of the working-age people wouldn't have been sent overseas to die & get maimed.
The point was we were never on a wartime economic footing in the same way were were in WW II.
It's probable that the War of 1812 showed America how unprepared it was for conflict with a serious power.
The civil war from 1861 to 1865 required the complete commitment of both sides, with the Union in particular developing massive industrial capacity to help the cause.
This rapid and urgent industrialization was further developed during the Reconstruction phase when a large chunk of the country had to be built back up from ruin.
If these two conflicts never happened there wouldn't have been the same urgency to develop industry. It would be much more of an agricultural economy like the southern states and not like Ohio, New York or Pennsylvania with their enormous appetite for large-scale manufacturing.
If that was the case the US would be utterly unprepared for any conflict in Europe. As it was the US military was in really rough shape prior to the outbreak of war in Europe. There was no pressing need for a large, well-equipped standing military since Mexic
Parts of the Cold War were peaceful for some countries (including the USSR), but the period in which the Soviets developed nuclear weapons (1943-1949) was a period during which the USSR was constantly involved in international armed conflict, and was absolutely not peacetime for the USSR.
That's very difficult to believe.
[1] https://www.ted.com/talks/malcolm_gladwell/transcript?langua...
[2] http://warfarehistorynetwork.com/daily/wwii/the-norden-bombs...
http://warfarehistorynetwork.com/daily/wwii/the-norden-bombs...
> ...the cost of the entire program came to more than $1 billion.
Russia developed nuclear weapons in peace-time as well, if you consider the cold war peaceful.
South Africa also produced some nuclear capability despite not being at war: https://en.wikipedia.org/wiki/South_Africa_and_weapons_of_ma... Naturally a country rich in uranium would be tempted to see what applications there were.