The search for a nuclear legacy

FIRST there was the “open mic” incident last March when Barack Obama assured his Russian opposite number, Dmitry Medvedev, that after his election he would have “flexibility” on the subject of missile defence. Then came the briefest of sentences, in his state-of-the-union address on February 12th, on the need to engage Russia in further reductions to nuclear arsenals. But together they give a clue to what could become a lasting legacy of Mr Obama’s two terms in office: a serious attempt to realise the commitment he made in Prague four years ago when he promised to take “concrete steps towards a world without nuclear weapons”.