Students from Liaoning University hold an activity at the 9.18 Historical Museum in Shenyang, capital of northeast China's Liaoning Province, Sept. 17, 2019. Air raid sirens once again sounded through Shenyang at 9:18 a.m. on Wednesday, the 25th time the northeastern Chinese city in Liaoning Province commemorated the day with the alarm. This year marks the 88th anniversary of the "Sept. 18 Incident," the start of Japan's invasion of China. (Xinhua/Yang Qing)

Representatives strike the bell together during a ceremony to mark the anniversary of the "Sept. 18 Incident" in Shenyang, capital of northeast China's Liaoning Province, Sept. 18, 2019. Air raid sirens once again sounded through Shenyang at 9:18 a.m. on Wednesday, the 25th time the northeastern Chinese city in Liaoning Province commemorated the day with the alarm. This year marks the 88th anniversary of the "Sept. 18 Incident," the start of Japan's invasion of China. (Xinhua/Long Lei)

A ceremony is held to mark the anniversary of the "Sept. 18 Incident" in Shenyang, capital of northeast China's Liaoning Province, Sept. 18, 2019. Air raid sirens once again sounded through Shenyang at 9:18 a.m. on Wednesday, the 25th time the northeastern Chinese city in Liaoning Province commemorated the day with the alarm. This year marks the 88th anniversary of the "Sept. 18 Incident," the start of Japan's invasion of China. (Xinhua/Long Lei)

A soldier attends a ceremony to mark the anniversary of the "Sept. 18 Incident" in Shenyang, capital of northeast China's Liaoning Province, Sept. 18, 2019. Air raid sirens once again sounded through Shenyang at 9:18 a.m. on Wednesday, the 25th time the northeastern Chinese city in Liaoning Province commemorated the day with the alarm. This year marks the 88th anniversary of the "Sept. 18 Incident," the start of Japan's invasion of China. (Xinhua/Long Lei)

People visit the 9.18 Historical Museum in Shenyang, capital of northeast China's Liaoning Province, Sept. 17, 2019. Air raid sirens once again sounded through Shenyang at 9:18 a.m. on Wednesday, the 25th time the northeastern Chinese city in Liaoning Province commemorated the day with the alarm. This year marks the 88th anniversary of the "Sept. 18 Incident," the start of Japan's invasion of China. (Xinhua/Yang Qing)

A man visits the 9.18 Historical Museum in Shenyang, capital of northeast China's Liaoning Province, Sept. 17, 2019. Air raid sirens once again sounded through Shenyang at 9:18 a.m. on Wednesday, the 25th time the northeastern Chinese city in Liaoning Province commemorated the day with the alarm. This year marks the 88th anniversary of the "Sept. 18 Incident," the start of Japan's invasion of China. (Xinhua/Yang Qing)