How was the USA/Russia able to build nuclear weapons in the 1940s, but countries today aren’t able to just as easily?

Question

How was the USA/Russia able to build nuclear weapons in the 1940s, but countries today aren’t able to just as easily?

In: Technology

Answer 1

There are international treaties and agreements in place that intentionally make it difficult. The Nuclear Non-Proliferation Treaty, nuclear-weapons-free zones, various export control regimes, and attentive monitoring by intelligence agencies and the International Atomic Energy Agency are all in place to make it so that if someone does try to develop nuclear weapons, they will be noticed, and then there are various kinds of ways (e.g. economic sanctions, political threats, actual acts of war) to punish them.

Additionally, most countries do not _want_ to develop the weapons: they don’t see a need. This is because they are either feel entirely non-threatened by them (e.g., they and their rivals are under a treaty that prohibits them), or they are under the “nuclear umbrella” of another nuclear state.

This system is not perfect, to be sure. Since it was put into place, Israel, India, Pakistan, South Africa, and North Korea each developed nuclear weapons. But it does seem to have slowed nuclear acquisition — there are only 9 nuclear states, not 20. The number of states that _could_ have nuclear weapons very quickly if they decided to is much larger than the number that have them.

It is not about lack of technical ability — it is much easier for a nation, technically, to build nuclear weapons today than it was in the 1940s, when there were many more “unknowns” and new things to learn.

The hitch of all of the above is that political circumstances can change. If Japan or South Korea suddenly felt like they was no longer protected by the US “nuclear umbrella” against China or North Korea, would they seek their own programs? There would be costs and consequences (sanctions, etc.), but it’s possible. Most of the trick to keeping nations from “going nuclear” has been in trying to make sure there were more advantages to them _not_ doing it than them doing it. Again, it hasn’t been perfect, but it works.