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

The U.S. Capitol building is seen through a barrier fence in Washington, D.C., the United States, Jan. 17, 2021. 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)