Washington D.C. mayor concerned about potential attack on city's residential area

Photo taken on Jan. 17, 2021 shows the U.S. Capitol building in Washington, D.C., the United States. Up to 25,000 National Guard members have been authorized for the city to ensure the security of Wednesday's inauguration, transforming the city into what some U.S. media called "a war zone." (Xinhua/Liu Jie)