Kim Jong-un, the North Korean leader, has accepted an invitation to attend a ceremony in Moscow on May 9 to mark the 70th anniversary of the Soviet Union's victory over Nazi Germany. The invitation was extended by Vladimir Putin, the Russian president, and will be the young dictator's first overseas trip since he became head of state after the death of his father, Kim Jong-il, in December 2011. While other world leaders might be reluctant to extend a welcoming hand to a pariah state that frequently threatens to turn the capital cities of its enemies to "seas of fire", Mr...