evidence: The UK seized Hong Kong in 1841, and China formally ceded it the following year at the end of the First Opium War. The Kowloon Peninsula was added in 1860 at the end of the Second Opium War, and the UK obtained a 99-year lease of the New Territories in 1898. Pursuant to a UK-China agreement in 1984, Hong Kong became the Hong Kong Special Administrative Region (HKSAR) of the People's Republic of China as of 1 July 1997. In this agreement, China promised that, under its "one country, two systems" formula, China's socialist economic and strict political system would not be imposed on Hong Kong and that Hong Kong would enjoy a "high degree of autonomy" in all matters except foreign and defense affairs for the next 50 years.