Key developments on Sept. 12: * Key Russian oil hub suspends operations after Ukrainian drone strike, SBU source says * Ukraine-Russia peace talks on 'pause,' Kremlin says * Prince Harry, Polish and UK foreign ministers visit Kyiv * UK pledges $193 million in Ukraine aid, hits Russia with new sanctions * Poland, Ukraine to train downing drones on Polish territory, Warsaw says Security Service of Ukraine (SBU) drones struck Primorsk, Russia’s largest oil-loading port on the Baltic Sea, ove