This undated copied file photo shows invading Japanese bombers flying over southwest China's Chongqing, which was China's wartime capital after the Japanese invasion. A batch of file photos recording the destruction of Chongqing and the hardship of people in the city during the anti-Japanese war were released by the city's Beibei District Archive on June 5, 2015. From February 1938 to December 1943, Japanese aggressors conducted terror blasts against Chongqing and its adjacent areas with over 11,500 bombs, mainly incendiary bombs, killing tens of thousands of civilians. (Xinhua)

This undated copied file photo shows invading Japanese bombers preparing for bombing southwest China's Chongqing, which was China's wartime capital after the Japanese invasion. A batch of file photos recording the destruction of Chongqing and the hardship of people in the city during the anti-Japanese war were released by the city's Beibei District Archive on June 5, 2015. From February 1938 to December 1943, Japanese aggressors conducted terror blasts against Chongqing and its adjacent areas with over 11,500 bombs, mainly incendiary bombs, killing tens of thousands of civilians. (Xinhua)

This undated copied file photo shows invading Japanese troops after bombing southwest China's Chongqing, which was China's wartime capital after the Japanese invasion. A batch of file photos recording the destruction of Chongqing and the hardship of people in the city during the anti-Japanese war were released by the city's Beibei District Archive on June 5, 2015. From February 1938 to December 1943, Japanese aggressors conducted terror blasts against Chongqing and its adjacent areas with over 11,500 bombs, mainly incendiary bombs, killing tens of thousands of civilians. (Xinhua)

This copied file photo taken in 1940 shows invading Japanese bombers flying over southwest China's Chongqing, which was China's wartime capital after the Japanese invasion. A batch of file photos recording the destruction of Chongqing and the hardship of people in the city during the anti-Japanese war were released by the city's Beibei District Archive on June 5, 2015. From February 1938 to December 1943, Japanese aggressors conducted terror blasts against Chongqing and its adjacent areas with over 11,500 bombs, mainly incendiary bombs, killing tens of thousands of civilians. (Xinhua)

This copied file photo taken in September 1940 shows dowtown Chongqing after being airstriked by Japanese bombers. A batch of file photos recording the destruction of Chongqing and the hardship of people in the city during the anti-Japanese war were released by the city's Beibei District Archive on June 5, 2015. From February 1938 to December 1943, Japanese aggressors conducted terror blasts against Chongqing and its adjacent areas with over 11,500 bombs, mainly incendiary bombs, killing tens of thousands of civilians. (Xinhua)

This copied photo taken in 1940 shows an aerial view of dowtown Chongqing after being airstriked by Japanese bombers. A batch of file photos recording the destruction of Chongqing and the hardship of people in the city during the anti-Japanese war were released by the city's Beibei District Archive on June 5, 2015. From February 1938 to December 1943, Japanese aggressors conducted terror blasts against Chongqing and its adjacent areas with over 11,500 bombs, mainly incendiary bombs, killing tens of thousands of civilians. (Xinhua)

This undated copied file photo shows invading Japanese bombers flying over southwest China's Chongqing, which was China's wartime capital after the Japanese invasion. A batch of file photos recording the destruction of Chongqing and the hardship of people in the city during the anti-Japanese war were released by the city's Beibei District Archive on June 5, 2015. From February 1938 to December 1943, Japanese aggressors conducted terror blasts against Chongqing and its adjacent areas with over 11,500 bombs, mainly incendiary bombs, killing tens of thousands of civilians. (Xinhua)