The Ministry of State Security (MSS) is the principal civilian intelligence, security and secret police agency of the People's Republic of China, responsible for foreign intelligence, counterintelligence, and the political security of the Chinese Communist Party (CCP). One of the largest and most secretive intelligence organizations in the world, it maintains powerful branches at the provincial, city, municipality and township levels throughout China. The ministry's headquarters are Yidongyuan, in Beijing's Haidian district.