@BevelGear That’s a tough question, but I think this is achievable, even in the current times. Top of my head come two things that make me think this would be doable, based on historical events:

1. Fear (generaly of WMD) and cost: As cynical as it could sound, if people get too afraid, they might not resort to war in order to solve their problems. The Cold War showed this: two hostile superpowers, owning the bulk of nuclear weapons on Earth, never got to war directly one against the other. India and Pakistan are both nuclear states, yet they did not escalate any skirmish to a full-blown conflict. Same as India and China. As for Ukraine, well, you can see what happened after the Budapest Memorandum - none of the signing parts managed to properly and adequately protect it from aggression, one being the aggressor itself. While it is true that Ukraine also invaded parts of Russia in the meanwhile, as a retaliation, we’re not sure to which extent the nuclear arsenal of the latter is still working, and the West has been very reluctant on allowing Ukraine to strike inside Russia using their weapons, due to this exact same reason, so the point still stands. Basically, if the aggressor has to pay a high price for invading another country and suffer retaliatory measures coming up from the aggressed country, the aggressor will be deterred.
2. Democracy (the true one, not the Russia style one): This also fits into cost, but it also lowers the level to which the cost of an invasion is acceptable. All military actions are decided by the leaders of the various countries. In a dictatorship, the cost the dictators have to face is pretty low by their standards. True democracies are less warmongering. You’ll never see a democratic country being at risk of waging war against others. That is because the cost that a leader can suffer due to war can be pretty high: they can lose their seat, their party might lose power, and they can even be jailed if various misdemeanors can happen (civilian casualties, war crimes etc.). That’s one of the reasons why Western made weapons are in such a low number and so high-tech and so precise, compared to the older Soviet-style weapons manufactured in my part of the world (who are more designed to be used en-masse to achieve the same efficiency) - the cost of using them by the militaries has to be lower. More importantly, democracies rarely, if ever, wage wars against one another. I cannot really explain this situation, but all I know is that it just happens. Democracies however have a chance of waging war against autocracies, out of fear that the democratic system might be threatened by them. They are more commonly seen as a way to defend themselves.

While I do not know, this makes you feel better, I do hope you now know where to look if you want to find a better answer 😁 And no, I did not use ChatGPT or any AI for this (although I think it will now know the answer itself), I’m just an International Relations graduate. At least there’s some place where I can put my knowledge to good use, hurray!