People gather at a park on Memorial Day to honor fallen soldiers in Los Angeles, the United States, on May 27, 2019. (Photo: Xinhua)

A man is seen at a park on Memorial Day to honor fallen soldiers in Los Angeles, the United States, on May 27, 2019. (Photo: Xinhua)

People gather at a park on Memorial Day to honor fallen soldiers in Los Angeles, the United States, on May 27, 2019. (Photo: Xinhua)

Flags are seen at a park on Memorial Day to honor fallen soldiers in Los Angeles, the United States, on May 27, 2019. (Photo: Xinhua)

A woman and a child visit the San Francisco National Cemetery on Memorial Day in San Francisco, the United States, on May 27, 2019. (Photo: Xinhua)

A man walks among flags at the San Francisco National Cemetery on Memorial Day in San Francisco, the United States, on May 27, 2019. (Photo: Xinhua)

People mourn at the San Francisco National Cemetery on Memorial Day in San Francisco, the United States, on May 27, 2019. (Photo: Xinhua)