Gansu was vulnerable to Soviet penetration via Xinjiang. Gansu was a passageway for Soviet war supplies for the Republic of China during the Second Sino-Japanese War. Lanzhou was a destination point via a road coming from Dihua (Ürümqi). The Gonxingdun Aerodrome was one of several air bases where the Chinese Air Force operated in defense of Gansu. Gansu provided wartime China with most of the locally-sourced petrol from the Yumen Laojunmiao oil wells beginning in the summer of 1939, producing 250,000 tons of crude oil in those war years. Lanzhou and Lhasa were designated to be recipients of a new railway.