AP Photo

Last week, on behalf of the Bulletin of the Atomic Scientists, I announced that the Doomsday Clock -- established in 1947 by scientists who had worked on the first atomic bomb in 1945 -- was to be moved back by one minute from its previous setting of five minutes to midnight -- five minutes to Doomsday. As of Jan. 14, it reads six minutes to midnight.

The Science and Security Board of the bulletin and its Board of Sponsors meet regularly to assess the changing global situation, and this is the 19th time the clock has been adjusted since its inception. It had last been reset in January 2007 and in 2002, following the events of 9/11. It was closest to midnight (two minutes) in 1953, when the United States and the Soviet Union tested thermonuclear weapons within six months of...