With the outbreak of the Sino-Japanese War in 1937, however, the future of these desert airports looked increasingly uncertain. The Nationalists ultimately were able to overtake Ejen-e. In an attempt to gain ground against the local warlord Ma Hongkui and his Muslim army, the Nationalists set out to establish a presence in western Inner Mongolia. They raided the Japanese special intelligence unit in Ejen-e and arrested the ten Japanese stationed there, including two Manchuria Aviation Company employees, and took them to Lanzhou for execution.
To counteract the Republican advance in Ejen-e, Ma Hongkui then attacked Alashan in 1938. Manchuria Aviation Company workers evacuated to Manchukuo, while the local prince hired coolies to hide the hundreds of canisters of gasoline in a secret chamber of a lamasery. Meanwhile a Japanese caravan carrying gasoline, ammunition, and supplies bound for Ejen-e inexplicably vanished into the Gobi, most likely captured by the Nationalists, with their three Manchuria Aviation Company handlers also sentenced to death in Lanzhou.