NATO allies are scouring their ranks — in search of a successor to Secretary-General Jens Stoltenberg. Stoltenberg, a former prime minister of Norway, has served in the top civilian post since October 2014. Allies extended his contract until September 2022, leaving little more than a year to install a replacement. At headquarters, formal discussions have just begun, and Stoltenberg’s successor is expected to be introduced at a NATO leaders’ summit in Madrid in late spring or early summer next year. But speculation in Brussels and other allied capitals is already rampant, with some o...