File photo copy shows Chinese forced labors working for Japan to build the Fengman hydropower station in Jilin of northeast China after the region was illegally occupied by Japanese invaders in 1931. Japan invaded northeast China in 1931 and conducted a full-scale invasion in 1937. By the end of World War II, millions of Chinese forced laborers had been enslaved by Japanese invaders to toil under harsh conditions at mines and factories in northeast China and Japan. Those laborers were under close watch and suffered inhumane treatment. Many of them died from malnutrition, illness, physical abuse and plain murder.