After 16 months of fighting in Ukraine, Russia's military still has nearly all of its combat aircraft, but neither Russian nor Ukrainian aircraft can control the air, the Royal Air Force's top general said Thursday. Jets and helicopters have not disappeared from over Ukraine, but thickets of air-defense systems make the airspace inhospitable. And even though Russia has a vastly larger air force, other issues may keep it from operating effectively, according to two NATO air commanders. In a speech at the Global Air & Space Chiefs' Conference in London on Thursday, Air Chief Marshal Rich Knighton, chief of the...