More airlines appear to have pulled back from flying over Ukraine after a U.S. warning that Russia could invade at any time, with flight insurance issues featuring in the background, and as a major European carrier announced a stop to overflights. Monitoring of flight tracking service FlightRadar24 showed the airspace over eastern Ukraine nearly empty at 6:58 a.m. New York time, with a strip of around a hundred miles in from the Ukraine-Russia border completely devoid of any flight traffic. Dutch airline KLM said it would halt flights to Ukraine and through the country’s airspace, with reports that other European carriers, including Germany’s Lufthansa, were reviewing their services to the country. Most of the 298 passengers killed when Malaysia Airlines MH17 was shot down over eastern Ukraine in 2014 were Dutch citizens. Russia has amassed around 130,000 troops, including artillery and other heavy equipment, close to Ukraine’s border. Moscow has …