The U.S. nuclear posture review (NPR) and the Ballistic Missile Defense Review, the main U.S. policy guidance for nuclear deterrence and defense, are scheduled to be released in a few weeks. According to the pre-decisional version of the NPR, unexpectedly leaked to the U.S. media in mid-January, it will most likely emphasize flexible, adaptable and resilient nuclear capability for the defense of the United States and allies given the dramatic deterioration of the strategic environment since the previous NPR took place in 2010.

While the report retains the long-term goal of eliminating nuclear weapons and importance of nuclear arms control, the main thrust of the NPR will be a departure from the major draw-down projection of strategic nuclear arms in the previous NPR, and bring the salience of nuclear domain back in the U.S. security strategy.

The key decisions of the new NPR will include sustaining and replacing the nuclear triad and nonstrategic nuclear capability, including a low-yield nuclear option. As for the declaratory policy, the new NPR will identify the role of U.S. nuclear forces to deter nuclear attacks of any scale by potential adversaries and also extend to the deterrence of potential adversaries’ non-nuclear strategic aggression, and to limit damage if deterrence fails. To achieve such goals, the U.S. will apply “a tailored and flexible approach to effectively deter across a spectrum of adversaries, threats and contexts.”

The nuclear disarmament community, as a matter of course, will strongly condemn the NPR’s decisions, saying they will lower the threshold of nuclear use and cause disarray in global moves toward nuclear disarmament. However, given the rapid strategic deterioration in Northeast Asia in the nuclear realm, there are enough reasons why America’s top allies in Asia — Japan and South Korea — should strongly support the key directions of the NPR decisions.

The North Korea challenge

Deterring North Korea has become more difficult as its nuclear weapons program has created wide-ranging strategic challenges. Its soon-to-be-ready intercontinental ballistic missile capability will raise allies’ doubts on U.S. resolve to launch a nuclear counterstrike at the expense of U.S. homeland vulnerability — a classic case of de-coupling.

Deterring North Korea in a crisis or during a conventional war will also become a difficult task. As North Korea’s escalation control capacity is limited, given its inferiority in conventional forces, Pyongyang will encounter a “use or lose” strategic choice to carry out full-scale nuclear attacks in the early phase of a conflict. On the contrary, if the U.S. nuclear retaliatory options are perceived to not be credible, North Korea may even think that limited nuclear strikes will provide a coercive advantage for its survival strategy.

These new sets of nuclear challenges — the classic de-coupling challenge, the “use or lose” perception and limited strike options — should be neutralized by the U.S. enhanced nuclear response capability, missile defenses and extended deterrence to allies. But these various scenarios require finely tuned flexible response options for the U.S. This is essentially why the precisely targeted low-yield nuclear counterforce strikes are important. In this vein, modifying submarine-launched ballistic missile warheads to provide a low-yield option and pursuing a modern nuclear-armed sea-launched cruise missile, together with development of the Long-Range Stand-Off cruise missile — all of which are suggested in the NPR draft — are particularly important to fill the exploitable gap in U.S. deterrence in Northeast Asia.

China’s nuclear strategy

While the pursuit of “strategic stability” with China mentioned in the 2010 NPR appears to be missing from the new NPR, Washington’s desire to seek dialogue to enhance mutual understanding with Beijing on nuclear policy remains in existence. However, the new NPR deliberately raises alarms over the increasing practicality of China’s nuclear forces since it concerns Beijing’s potential perceptions to secure an advantage through the “limited use of its theater nuclear capabilities or that of any nuclear weapons.”

Japan, too, is paying more attention to Chinese conventional military capability that creates an anti-access/area denial environment for U.S. operational access to the region, and China’s limited use of nuclear weapons within its escalation control strategy. In this regard, the NPR decision to “respond decisively to Chinese non-nuclear or nuclear aggression” through a range of graduated nuclear response options are of significant assurance value to allies in Asia.

Meanwhile, as China’s strategic and theater nuclear forces become more survivable and robust, de facto mutual vulnerability in U.S.-China nuclear relations seems to prevail in the long run. This anticipated future reveals various forms of de-coupling in alliance relations: First, mutual vulnerability at the strategic level (U.S.-China relations) will not ensure regional stability in Asia (Japan-China relations). Second, if the U.S. tries to deny strategic stability with a potential increase of U.S. homeland missile defense (ground-based interceptors), it will also incentivize China to focus on nuclear deterrence strategy in the region. Third, the U.S. conventional operational access concept will also trigger China to use nonstrategic nuclear weapons in escalation control.

As there are increasing difficulties in pursuing a “best mix”of deterrence and assurance in the region, the U.S. needs constant updates and consultation with its allies regarding a tailored nuclear strategy in Asia beyond NPR 2018.

Ken Jimbo is an associate professor at Keio University.

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