The incoming Biden administration will need to quickly extend the New START nuclear pact before it expires on Feb. 5. Russia has previously offered a five-year extension, consistent with the treaty’s terms. That extension will, however, be only the first step in a long process to return nuclear arms control from the brink.

The Trump administration tentatively agreed with Moscow to a one-year extension accompanied by a freeze on all nuclear warheads. But that effort faltered on verification issues. The Biden team has indicated support for an unconditional extension and appears to favor a longer time period. Given the complexities, providing negotiators the full five years would avoid setting an early deadline that might pressure Washington. The negotiators will need to wrangle with several complex interconnected issues.

Current limitations on deployed strategic warheads and launchers should be lowered. The current warhead limit of 1,550 has been met by both sides, and parity exists in this category. In new negotiations, the ceiling might be lowered to about 1,000, which is close to the number the U.S. military said in 2013 that it could accept. That would further reduce the risk to each side of a disabling first strike.

The deployed launcher limit of 700 (which includes deployed intercontinental ballistic missiles, submarine-launched ballistic missiles and nuclear-capable bombers) might also be lowered but not too far since a small number would make attractive targets for a first strike.

These deployed strategic systems are potentially the most destabilizing and the easiest to verify, so they should be given priority.

Next, Russia’s agreement to a temporary freeze of all warheads has prompted some to urge that a subsequent START agreement should also cover warheads that are in storage. Imbalances exist in this category, with Russia holding about 3,000 warheads in storage and the United States holding about 2,400. Within these totals, Russia has a strong advantage in nonstrategic warheads, which can destabilize regional security.

A simple freeze on these systems would not be a credible, long-term solution since it would lock in an American disparity. But the imbalance in nonstrategic systems has our European allies worried, particularly in the wake of the demise of the Intermediate-Range Nuclear Forces Treaty, which opens the door to Russian midrange missile deployments that can strike them. Deep cuts in stored warheads to a common cap of about 1,500 each, with possible sub-ceilings on nonstrategic warheads, would thus also be a good outcome for the U.S. and its allies. Verification of stored warheads, however, would require more intrusive measures, which Russian negotiators are reluctant to accept.

To realize these nuclear reductions, negotiators will need to tackle a series of destabilizing events that have taken place in the past two decades which together have unhinged the previous consensus on what constitutes strategic stability — namely each side retaining a second-strike retaliatory capability.

The United States, responding to nuclear proliferation and terrorist threats, abandoned the Anti-Ballistic Missile Treaty in 2002 and is considering options for a hypersonic conventional-prompt global strike capability.

Russia fears that this combination of conventional-prompt global strike and missile defenses could give the U.S. the ability to strike first and deflect any retaliatory strike. As a result, Moscow is developing six new delivery systems designed to defeat U.S. defenses, including a deployed hypersonic glide vehicle (Avangard), a nuclear-powered cruise missile (Skyfall) and a hypersonic cruise missile (Tsirkon). Some analysts in the U.S. see these new Russian systems as destabilizing.

Left unsettled, these changes will undercut efforts at further warhead reductions and lock in a dangerous sense of strategic vulnerability on both sides. But reversing these developments will be difficult.

Limits on missile defenses will need to be discussed, but Senate ratification of a second Anti-Ballistic Missile Treaty is very doubtful. If further anti-ballistic missile limits are agreed, those limits would need to provide for adequate U.S. interceptors to deal with proliferation threats from states like North Korea and Iran. Congressional approval might be reached with simple majority approval of both chambers, as was the case with the Strategic Arms Limitation Treaty I.

Limits on Russia’s new systems and America’s conventional-prompt global strike program may also need to be reached, either in the START negotiations or in a separate agreement.

In the context of limits on nonstrategic weapons, negotiators might also seek ways to resurrect elements of the abandoned INF Treaty. One option is banning all intermediate-range (500-5,500 kilometers), ground-based missiles that are armed with nuclear warheads. Alternatively, intermediate-range missiles might be excluded from a zone that is in range of NATO targets. Russia has offered a verification proposal that may enable a revised INF Treaty.

Finally, as Chinese nuclear capabilities grow, there is pressure to include China in any future START pact. China is, however, unlikely to want to engage since it has just over 300 nuclear warheads, or less than 10 percent of the number of deployed and stored warheads held by Russia and the U.S. If China is included, there will be further pressure on Britain and France to limit their warhead numbers as well, something our close allies may resist. A good outcome might be if the United States and Russia together press China to freeze its current nuclear warhead numbers as long as the two START parties stay within their new reduced limits.

To set the stage for successful negotiations with Russia, the U.S. should first propose bilateral talks to regain some common understanding of what constitutes strategic stability. In addition to the issues discussed above, those talks would need to examine the nuclear doctrine of both sides. Russia’s “escalate to de-escalate” doctrine implies Russian willingness to be the first to use nuclear weapons, further destabilizing things in a time of crisis.

The Russians may have similar concerns about the United States after the 2018 Nuclear Posture Review. These talks might also discuss a code of conduct and other steps relating to the security of each side’s command-and-control arrangements to ensure that critical cyber systems remain secure and are not corrupted.

And to set the stage for subsequent congressional approval of any deal, the Biden administration should reconstitute a congressional arms control observer group that can monitor the negotiations and hopefully serve as validators when Congress eventually considers the agreements.

President-elect Joe Biden will have an experienced team to sort through these complicated issues. But it will take time and creativity to be successful. Given the poor state of U.S.-Russian relations, success here could be an important step in the right direction.

Hans Binnendijk is a distinguished fellow at the Atlantic Council. He previously served as the National Security Council’s senior director for defense and arms control and as director of the National Defense University’s Institute for National Strategic Studies.

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