Actually. come to think of it - its a Dirty Bomb that is actually the worry. Russia or China are not going to get into an all out war, especially using nuclear weapons. The moment one side ups their ante to nuclear - a holocaust will follow. I don't think starting a nuclear war and jeopardizing mankind's future is high on either Xi Jinping or Putin's bucket list. They will wax eloquent about nationalism, they will dance around the trigger but they will not pull it. Its the non-state actors which are actually the worry. The illicit sale of arms in dark markets across the world. The UN should certainly come together to address this.