Key developments on Sept. 23: * Trump says NATO should down Russian aircraft violating allied airspace * Zelensky, Trump meet in New York amid surging Russia-NATO tensions * Ukraine hits Russian oil facilities in Bryansk, Samara oblasts, military claims * Ukrainian drones attacked Moscow throughout the night, mayor says * Russia not close to encirclement of Kupiansk in Kharkiv Oblast despite claims, expert says U.S. President Donald Trump said on Sept. 23 that NATO countries should shoot
