Following the Sino-Soviet conflict, the Soviet authorities demanded that all White Russians had to be dismissed from both the Northeastern Army and the Chinese Eastern Railway, while their leaders, among them Nechaev, were to be expelled from Manchuria. Nechaev consequently fully retired from military service, but remained in Manchuria, where he became head of two White émigré community organizations: The "Russian National Community" in 1930, and later the "Bureau of Russian Emigrants in Manchuria". He continued to live in Manchuria after the Japanese invasion of 1931, and the establishment of Manchukuo. The Soviet Union invaded Manchuko in 1945, and arrested numerous White Russians living there. Nechaev was among those captured by SMERSH and sent to the Russian Soviet Federative Socialist Republic. Tried by before the 6th Guards Tank Army's military tribunal, he was sentenced to death in November 1945, and subsequently executed by hanging in Chita in 1946. He was rehabilitated by the Transbaikal Military District in April 1992.