China has warned that it could send troops to Hong Kong to deal with pro-democracy protests. The Beijing government released a new defense strategy Wednesday and, during a news conference marking its publication, chief spokesman for the ministry of national defense, Senior Col. Wu Qian, said: “The behavior of some radical protesters challenges the central government’s authority, touching on the bottom line principle of ‘one country, two systems’... That absolutely cannot be tolerated.” The New York Times reports he then referred to an article in the constitution of Hong Kong that allows the People’s Liberation Army to intervene to maintain order when asked by Hong Kong’s leaders. The defense strategy also refused to rule out the use of force against Taiwan, and accused the U.S. of attempting to undermine global stability.