Making nuclear weapons is much easier than it used be. Germany and Japan could both enrich Uranium from their civilian nuclear programs in weeks or months if they wanted to. (but nobody is worried they will, largely because of their allies and the history of them not doing so)

(we 'stop' other nations from acquiring weapons by offering them access to civilian nuclear power - via the NNP treaty - but this didn't work to stop India or Pakistan.)

That said there are two difficult steps - enriching Uranium, with centrifuges operating on Uranium gases (probably Uranium Fluoride) and once you have enriched enough a bomb is really easy to make (rockets are still much more difficult, but i'm sure another delivery system could be used)

Plutonium weapons also involve a difficult step, it is much easier to get your hands on Plutonium (from a nuclear reactor) but requires an implosion which is very complicated (though i guess modern computers could simulate the required shock-wave fronts... )

The solution? Support states, have them included in the international community to the point where they have more to lose by being left out.

The Marshal plan is a great example, the US supporting the rebuilding of Europe (because what happened after world war 1 in germany was a terrible result of that war) and including western europe (along with Japan, as it happens) in the American 'empire' a commercial enterprise - This allowed Europeans buy US goods and defend themselves from the Soviet Union (i'm sure different parts of the American political system were more or less interested in each of these goals, but both goals were achieved)

To include nations like Iran and North Korea (well you might want first to resolve the Korean war, and unify North and South... ) in the international community, give them more so they don't have more to lose from war than they can possibly gain...

China is not a threat to 'world stability' because it is thriving on the trade relationships it has with the US, Russia, Africa, and Europe.... How to include Korea or Iran is a difficult question, but that is what you should be asking.

The thing about the Marshall Plan is that it was incredibly expensive. It's safe to say now that it was a major success and in my mind on of the real high points in American history, especially after a tragic turn with the wars, but it would be near impossible to accomplish today for any of the seven powerful nations but Germany. The rest have their own issues to deal with, as does Germany, but once Berlin is fully built up again thy should be okay to start importing more like they did before the wars. If nuclear power is going to work the same way, it certainly will be awhile before the United States (or another power) can intervene in order to assist another nation in building up without having to use nuclear power.

@bo_sox:
"@Steephie ... the Marshall Plan is one of the most notably one-sided deals in history. It was out of pure desire to repair Europe. Some would argue that they expected repayment, but they certainly weren't expecting physical compensation."

Again, I disagree with the word pure... How about strengthening capitalism? Weakening communism? Also it was good for their economy right?

Orthaic, I think you're overstating the simplicity of creating a bomb. For the bomb to have a nuclear explosion and not just be a dirty conventional bomb, the geometry, timing, and electronics are quite advanced. Now, I have no idea how realized these technologies are in non-nuclear states. It may be a relatively small speed bump like you suggest but I wouldn't be so quick to dismiss it.

The Marshall Plan was not intended to weaken communism or strengthen capitalism. Be mindful that the aid was offered to the Soviet Union as well, though I'm sure the United States didn't want to do so. When the USSR rejected it, the leaders of the US probably rejoiced and drank all night.

@Yonni, Uranium fission bombs are really easy - once you can enrich them, you can accidentally set them off. (no problems with geometry, or timing, but the enrichment is difficult)

Plutonium bombs on the other hand are really tough. (much easier to enrich, but it blows itself apart before the chain reaction has a chance to use up all the fuel, thus leaving you with a dirty bomb...)

But of all the difficulties, technology has gotten easier since the 40s when the US and USR first managed to build their nukes.

India had enriched Uranium from it's civilian program, and just had to enrich to a higher percentage - and had help from the international community building this civilian program.

The marshal plan meant peace in Europe, which was exactly the opposite of the treaty of Versailles after world war 1. You have to look at it not from the perspective of the cold war and the eventual development of the European Union, look at it as a lesson learned from the first world war, and the same mistakes not being repeated.

"The Marshall Plan was not intended to weaken communism or strengthen capitalism. Be mindful that the aid was offered to the Soviet Union as well, though I'm sure the United States didn't want to do so. When the USSR rejected it, the leaders of the US probably rejoiced and drank all night." Russians rejected because it would strengthen capitalism and weaken communism... So why wouldn't that be the reason for Americans to offer it in the first place? If Russia accepted they probably wouldn't have stayed communists much longer, right? And peace works for the US too of course...

Again, I agree it's a good move, but I think it's not really that purely to help the people, they gained from it themselves too...

How would that strengthen capitalism? It would simply allow Russia to rebuild with someone else's money. They said no because they didn't want to accept the American help, not because they thought it would strengthen America.