"Stopped" is a strong word. Nuclear proliferation and chemical weapons are ongoing and increasing threats. I'd bet a lot of money that we'll see the use of space weapons in our lifetime.
In regard to chemical weapons, they are decreasing danger because they are not effective in modern warfare. I'd expect for their usage to decrease. Nuclear is is not something proliferating besides North Korea and even then it is deturance and not an appocaliptic scenario. Space weapons are forbidden by treaty and though some countries are playing close to the read line, I doubt that they will be deployed. They would be political liability while being rather vulnerable in space. Hence hypersonic weapons which work better for the same goals.
Iran is the exception that confirms the rule. They were so heavily sanctioned that it became feasible for them to say "screw it, we will do nukes anyway". I won't say that nuclear proliferation is completely stopped, but the system works for the most part. China and Russia are old nuclear powers and them having nukes is expected.
Better counter examples are India and Pakistan, but I don't know the history of their nuclear programs well enough to comment with confidence.
The chemical weapons in Syria were old stockpiles and I'd argue that the use there was not an increase of their use, but an opportunity attack. I don't think that there are many groups who currently have any kind of chemical program and can use it systematically.
Not so much chemical weapons. They're simply not that useful. Their appeal has been niche for decades, and shrinks by the year, even if you took politics completely out of it.
Nukes, yes. International pressure is the only reason at least a dozen more countries don't have nuke programs, than do today.
It’s only states that can afford nukes and also want them that badly. Terrorists would love them, and wouldn’t care about sanctions, but they can’t afford them. Large corporations might be able to afford them, but they don’t have a use for them.
AI just keeps getting cheaper, and demand is mostly non-government.
