Because of decisions likely to be taken this year and next, nuclear weapons will become a normalized and permanent part of the 21st-century American arsenal, and therefore of the arsenals of many other nations; nuclear weapons, that is, will have become an essential element of the human future -- as long as that future lasts.
In 2014 there are more nuclear weapons than ever, but we don't really talk about them very much. Instead we talk, primarily about the possibility of human extinction due to climate change, food shortages, ocean acidification or, occasionally, super-volcanos or comet collisions. All of these things are possible, and all of them are very unlikely to cause the extinction of humanity.
After the Cold War, the American self-image became that of the "sole superpower." We were the only 800-pound gorilla in the world, and therefore we could do what we pleased without having to worry about any other country's ability to stop us. Russia, under Putin, is reasserting itself as the second weighty gorilla in the room.
From the actual nuclear destruction of 1945 to the prospective nuclear destruction that, in the Cuban Missile Crisis of 1962, seemed briefly to reach the edge of a world-ending boil, to the possibility today of a global "nuclear winter" set off by a regional war between India and Pakistan, who knows just how the fear of a nuclear apocalypse has embedded itself in consciousness.