Well, Europe was of central focus in the conflicts of World War 1 and World War 2, but now the European Union is a fairly peaceful place. There is of course still some crime, but in terms of war, their differences are a lot less. France and England have had countless wars over centuries, but now their disagreements are so much smaller and more civilized as allies. Germany works well with the rest of the European Union, and tends to have a leadership role in certain areas, especially financially. Who knows how long it will last, but I think it's a pretty unprecedented thing for so much peace, cooperation, and freedom of movement across Europe. On other continents there is still a lot of violence, especially parts of Asia and Africa.
Japan and South Korea have disagreements, but tend to be civil. Japan and the U.S. have been allies since World War 2. Japan and Korea are not exactly on friendly terms with China but the idea of a major war seems remote. In general, developed countries rarely have much war with each other these days- the idea never even really comes up. Instead it's mostly acts of aggression or over-response by developed countries towards lesser developed ones, or between lesser developed countries. I think some form of economic disintegration would have to occur before wars break out in most developed areas.