What would nuclear war look like in the 21st century?

IN 1960 America had around 18,000 nuclear weapons. It also had detailed plans for how to use them. Had it implemented them, 275m people in the Soviet Union would have been killed in the first hour of war. Another 325m would have died from radioactive fallout over the next six months. Even if China stayed out of this prospective war, the fallout would have killed perhaps 300m of its citizens.

“I thought of the Wannsee conference,” wrote John Rubel, an American defence official present at one nuclear-planning meeting, referring to a gathering of Nazis in a suburb of Berlin in January 1942, at which they prepared the systematic extermination of European Jews. “I felt as if I were witnessing a comparable descent into the deep heart of darkness.”