Local Chinese resistance forces , organized separately by both the communists and KMT , continued their resistance in occupied areas to pester the enemy and make their administration over the vast land area of China difficult . In 1940 , the Chinese Red Army launched a major offensive in north China , destroying railways and a major coal mine . These constant harassment and sabotage operations deeply frustrated the Imperial Japanese Army and led them to employ the " Three Alls Policy " ( kill all , loot all , burn all ) ( , Hanyu Pinyin : '' Sānguāng Zhèngcè '' , Japanese On : '' Sankō Seisaku '' ) . It was during this period that the bulk of Japanese war crimes were committed
Japanese war crimes
Japanese war crimes
Second Sino-Japanese War