You could make the argument that the only way these third world countries could've been prevented from getting their hands on nuclear weapons was if the decolonization movement didn't take hold and European / Asian imperialism still reigned the world.
we could also just take out the governments
If you take out the government you create playing grounds(=anarchy) for new warlords to set up kingdoms / create governments and tax their servants by force in exchange for protection against other warlords. Same thing happened after the fall of the Roman Empire. Lets not repeat history please.
ancap is not anarchist
So you're saying Anarchist Capitalism isn't anarchist?
"Ancaps are as much anarchists as Christian Scientists are scientists. Traditional anarchist movements originated on the left, and do not consider anarchy and capitalism to be compatible, and thus consider anarcho-capitalism not to be an authentic form of anarchism. Ancaps have proven to be one of the greatest tools for anarchist unity in living memory, as more or less every single major anarchist group and tendency stands united in despising them. Needless to say that socialists, communists, social democrats, liberals, and centrists aren't exactly fans of them either and will more than often unite even with the aforementioned anarchists to beat up on the ancap. Even Conservatives (even and especially of the Neo variety) aren't above taking the occasional pot shot at them."-
http://rationalwiki.org/wiki/Anarcho-capitalism
capitalism is inherently authoritarian
ancaps are just tards who want to be special