The U.S. State Department is investigating the shipment of computers and other sophisticated equipment to North Korea and Iran by way of an obscure United Nations agency, despite ongoing U.N. and U.S. sanctions against both governments aimed at blocking their development of nuclear weapons. The broadening inquiry raises new concerns about the ways in which U.N. agencies have managed to sidestep restrictions that the world body expects the rest of the world to obey in halting the spread of sensitive technologies to nuclear-ambitious pariah regimes. It also calls into question how much U.N. member states know about the activities of...