China tested its first successful nuclear weapon in October 1964. It developed its weapon without Soviet aid. Since then, China's nuclear policy has been one of "minimum deterrent" and has upheld the no first use pledge.  In the 1970s, after China began its policy of international openness, it began participating in the existing dialogue on non-proliferation and disarmament. China joined the International Atomic Energy Agency in 1984 and signed the Non-Proliferation Treaty in 1993.  To make transparent its policy towards nuclear weapons, China publishes a national defense white paper every two years, reiterating or adding to its stance on the matter. In the most recent white paper, published in May 2015, China emphasized that it would only use its nuclear weapons for two purposes: first, strategic deterrence and second, nuclear counterattack. 
An important addition to China's most recent white paper is the inclusion that the country seeks to "improve strategic early warning" for its nuclear arsenal.  To date, China's nuclear warning technology is not as advanced as that of Russia and the United States. However, China made several strides in 2015 including the development of a sea-based nuclear deterrent technology and the MIRV (multiple independently targetable reentry vehicle), which is a ballistic missile that consists of several warheads and can hit a group of targets at once. 
China outlines clearly when it will and will not use nuclear weapons:
China will not use nuclear weapons to attack or threaten non-nuclear states.
China will not use nuclear weapons to respond to conventional attacks.
China will use nuclear weapons only after it has confirmed an incoming nuclear attack. 
China has always supported nuclear disarmament. As such, its relationship with North Korea has been strained by the rogue nation's nuclear arms development. China is North Korea's most vital ally. China is the biggest exporter of food and energy to North Korea as well as its biggest trading partner.  In a diplomatic attempt to get North Korea to stall its nuclear agenda, China has become a key player in the Six Party Talks, an ongoing multilateral conference aimed at creating a disarmed North Korean state. Stability in the Korean Peninsula remains an utmost priority to the Chinese and it has striven to develop a strong diplomatic relationship with both North Korean and South Korea.  However, the United States and other P5+1 nations are unsatisfied with China's efforts. In January 2016, North Korea conducted a nuclear test. The United States called on China to use its influence to force the DPRK to forgo its nuclear weapons.  To date, while China condemned North Korea, it hasn't done anything concrete to deter the DPRK. Washington believes this is because China does not want to "make the North more aggressive or even push its government to collapse." 
Similarly, regarding Iran, China supported the Joint Comprehensive Plan of Action, which was agreed upon by the P5+1 (United States, China, United Kingdom, France, Russia and Germany) in July 2015. China began supporting sanctioning Iran in 2002 after revelations of Iran's Natanz facility became public.  While it is in its national interest to prevent nuclear aggression, it is also in China's interest to not strain the Sino-American relationship, arguably the most important bilateral relationship today. 
China's nuclear policy remains one that supports non-proliferation and disarmament. However, due to its historically strong relationship with North Korea, it has hesitated to spearhead measures beyond diplomatic dialogue and condemnation.
© Caitlin Lu. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
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