Where is North Korea not on this list? Right...they have nuclear weapons. The surefire way of preventing invasion & war. That's why the Great War isn't going to happen again. If WWIII does happen it's game over folks.
Nuclear weapons are the reason why the competing global powers have found new ways to compete and project power abroad. Global wars have mostly moved from being violence-based to being fought via propaganda and economics. It probably mirrors the way smaller communities moved from physical to intellectual competition.