What are some examples of important geopolitical problems facing the world community at the end of the 20th century?

Geopolitical problems of the late 20th century:
1) The collapse of the USSR. The 15 republics became separate states again, which led to a large number of conflicts.
2) The countries adhered to a militaristic policy, which was also a big problem.
3) The demographic problem, somewhere there is a crisis, but somewhere there is a big overpopulation.
4) Terrorism.
5) And various environmental issues can be added here too.