A nuclear nightmare

BARACK OBAMA began his presidency with an impassioned plea for a world without nuclear weapons. This week, in his last year in office (and as we went to press), he was to become the first American president to visit Hiroshima, site of one of only two nuclear attacks. Mr Obama has made progress on nuclear-arms reduction and non-proliferation. He signed a strategic-arms-control treaty (New START) with Russia in 2010. A series of nuclear-security summits helped stop fissile material getting into the wrong hands. Most important, he secured a deal in July to curtail and then constrain Iran’s nuclear programme for at least the next 10-15 years.But in one area, his failure is glaring. On Mr Obama’s watch the nuclear-weapons and missile programme of North Korea has become steadily more alarming. Its nuclear missiles already threaten South Korea and Japan. Sometime during the second term of Mr Obama’s successor, they are likely also to be able to strike New York. Mr Obama put North Korea on the back burner. Whoever becomes America’s next president will not have that luxury.