You Japanese have a completely different kind of problem. Your country has an advanced economy but far too conservative culture. This leads to a cultural gap between the young and the old. The young are so concerned about being successful that they don't even bother to make a family and have children. Young people's suicide rates are too high. A young population that is too small cannot take care of the elderly, and the elderly become an economic burden. And the Japanese xenophobia that does not allow immigration contributes to the declining demography. That's a national catastrophe that you have there, Shiroi.
Of course in the third world the problem is reversed: overpopulation leads to a situation in which young people can't get jobs. They are frustrated and start revolutions, and this creates anarchy and violence, which leads to terrifying phenomena like ISIL.
The world states depends on each other more than ever today. In a reality of immense immigration and civil wars, the policy of non-intervention would not do. If you do not stop a catastrophe in a different state, you could quickly find it at your back door.