Current Nuclear Threats in East Asia Tong Zhao Program on Science and Global Security, Princeton University; Carnegie Endowment for International Peace Japan Physical Society, 9 PM US ET, Tuesday, 21 March 2023

Main changes in China’s nuclear policy • Change in numbers • Open source research: • For decades: ~200 weapons • 2015: ~230 • 2018: ~280 • 2021: ~350 • 2023; ~400 • DoD annual report to Congress: • 700 in 2027; 1,000 in 2030; 1,500 by 2035 • Other estimates • Change in structure: nuclear triad (now publicly mentioned) • ICBM silos • Road-mobile ICBMs • SSBNs • Strategic bombers • Change in narratives • “lean and effective” • 2021: “high-level strategic deterrent… system” • 2022: “powerful strategic deterrent capabilities system”

Fissile materials as the main bottleneck • Two CFR-600 Demonstration Fast Reactors, Fujian Province • Described as part of “Civil-Military Fusion” program • Civilian Reprocessing Pilot Plant, Gansu Province • Stopped reporting to IAEA since 2017 • 200 tHM/year Demonstration Reprocessing Plant, Gansu Province • Under construction • Two plants in total are being built • 2022 NPT Review Conference: deletion of the call for a moratorium on fissile materials 3

Technical level drivers • New technological threats to China’s nuclear deterrent • Missile defense, CPGS, advanced sensors, cyber, etc. • Missile defense: • Worst-case scenario thinking; even a small U.S. homeland missile defense system could be threatening • Demise of the INF treaty • Limitation of technical-level factors • Lack of abrupt change of U.S. capability or policy • Silos not ideal for addressing missile defense concern (primary Chinese technical concern) • Chinese officials cited other reasons (safety and security) • Chinese experts not aware of nuclear buildup and do not understand the rationale

Political-level factors • All Chinese paramount leaders emphasized the political value of nuclear weapons • Mao Zedong: imperialist countries “look down upon us because we don’t have atomic bombs and only have grenades…therefore China should have atomic bombs and develop hydrogen bombs as soon as possible.” • Deng Xiaoping: “If China had not had atomic and hydrogen bombs and launched satellites since the 1960s, it would not have been able to be called a major power with significant influence and would not have had the international status it has now.” • Deng also pointed out: if China was to have a higher status and more say in the future world order, it must be backed by a strong nuclear power. • Jiang Zemin: “strive to build a lean and effective strategic nuclear force commensurate with China's great power status.” • Hu Jintao: “build a strategic missile force commensurate with China’s major power status.” • What’s new under Mr. Xi • He believes China’s success at achieving “great power status” today causes a fundamental problem • Structural force in international relations • Power-centric mindset • Nuclear weapons are the ultimate demonstration of strategic capabilities • Emphasis on warfighting as demonstration of political loyalty? • “fighting spirit” • New role for PLARF: “strategic balance” (战略制衡)、”strategic deterrent and control” (战略慑控)、and “strategic decisive victory” (战 略决胜) • Early warning and launch under attack

Nuclear risk over the Taiwan Strait • Taiwan Strait conflict a growing concern for Japan • A new sense of urgency in China under Mr. Xi • A military option by 2027 • Pushing nuclear to the forefront of China-U.S. security relationship • Growing Chinese interest in developing nuclear escalation management capabilities. • Departure from massive retaliation doctrine • Proportional retaliation against regional targets • More accurate theater-range nuclear systems • Uncertain Chinese interest in low-yield nuclear weapons • US W76-2 warhead yield: ~5 kt 6

Russia-China nuclear cooperation • Missile defense; early warning; joint strategic bomber patrols • Future possibilities? • Mr. Xi’s visit to Russia • Nuclear submarine technologies (AUKUS)? • Sharing bases and facilities? • 2022 U.S. Nuclear Posture Review • Two nuclear near-peer competitors 7

DPRK’s rapid nuclear expansion • Simultaneous development of strategic and tactical nuclear weapons • Ambition to acquire a secure second-strike capability against the U.S. homeland • Compare with China • Destabilizing impact of tactical nuclear weapons • Even more dangerous, as other countries (such as South Korea) also increasingly reply on rapid response • Bottleneck • Fissile material • Political costs of conducting nuclear and ICBM tests. 8

How Japanese scholars/scientists can help? • Political measures • Understand negative impact of information/perception gap on China’s own interests • Promote a No-First-Use debate? • Only issue that China is interested in discussing, but Japan traditionally opposes • A limited Taiwan Strait NFU between the U.S. and China? • A limited Korean Peninsula NFU zone? • Promote a regional dialogue on tactical nuclear weapons? • With a focus on Korean Peninsula • Specific technical-level nuclear policy measures • Raise awareness of consequences of a nuclear conflict • Including the consequences for Chinese people (even Chinese experts are not necessarily aware) • Joint expert study on radioactive impact of a region nuclear conflict? • Clarify misunderstandings on specific policy issues • Joint expert study on Fukushima waste water discharge? • Joint expert study on potential lessons of Japan’s Rokkasho plant for China’s plan to build a 800 tHM/year reprocessing facility? • Empower Chinese experts • Chinese experts are increasingly marginalized in domestic decision-making • Joint regional expert-level dialogues (China-ROK-Japan)? 9