SEOUL, South Korea — North Korean Supreme Leader Kim Jong-un and Russian State Duma Speaker Vyacheslav Volodin unveiled a statue Sunday in Pyongyang honoring the North Korean troops who helped Russian forces repel an incursion into Kursk Oblast. The event indicates that ties between Russia and the only state to send troops to join the Kremlin’s forces on the battlefield remain warm — at a time when Kiev may finally be stemming Moscow’s advance. Mr. Kim and Mr. Volodin cut a ribbon to unveil the