Laothoe populi, I would say, rather than Laothoe amurensis, which looks almost identical, besides the reddish part on the underwing, which, however, I cannot see in your pictures. But the range let me also think rather Populi than Amurensis.
http://tpittaway.tripod.com/sphinx/l_pop.htm
http://tpittaway.tripod.com/sphinx/l_amu.htm
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