The United Nations Security Council has convened an urgent meeting on America's missile development. Thursday's session was at the request of Russia and China, following Washington's test of an intermediate-range cruise missile on August 18, some two weeks after the U.S. pulled out of the Intermediate-Range Nuclear Forces Treaty. China's defense ministry said Beijing would not take part in a trilateral disarmament agreement. CGTN talked to Su Xiaohui, a senior researcher at the China Institute of International Studies. She explained the reasons behind the Chinese announcement.