As with many Allied countries in World War II, the Soviet Union received Western aircraft through Lend-Lease, mostly Bell P-39 Airacobras, Bell P-63 Kingcobras, Curtiss P-40 Kittyhawks, Douglas A-20 Havocs, Hawker Hurricanes, and North American B-25 Mitchells. Some of these aircraft arrived in the Soviet Union in time to participate in the Battle of Moscow, and in particular with the PVO or Soviet Air Defence Forces. Soviet fliers in P-39s scored the highest individual kill totals of any ever to fly a U.S. aircraft. Two air regiments were equipped with Spitfire Mk.Vbs in early 1943 but immediately experienced unrelenting losses due to friendly fire as the British aircraft looked too much like the German Bf 109. Lend-Lease aircraft from the U.S. and UK accounted for nearly 12% of total Soviet air power.