The Democratic Party platform states that Democrats believe that the “sole purpose” of U.S. nuclear weapons should be to deter and—if necessary, retaliate against—a nuclear attack. Presidential candidate Joe Biden has said the same. The sole purpose would mark a significant change in U.S. nuclear policy, eliminating ambiguity that preserves the option to use nuclear weapons first in response to a conventional attack. Adopting the sole purpose is a sensible step that would foreclose an option that no president has ever chosen . . . or ever would. 

Extreme Circumstances 

The U.S. government has long taken the position that it would use nuclear weapons only in “extreme circumstances” in which the vital interests of the United States, its allies or partners were at stake. That formulation leaves ambiguity as to whether an American president might in some cases decide to use nuclear weapons first. Indeed, it explicitly preserves that possibility.

When the Soviet Union and Warsaw Pact held large numerical advantages in conventional military forces during the Cold War, U.S. and NATO officials maintained an explicit option for deliberate escalation to nuclear weapons in the event of a conflict where they were losing at the conventional level. That might have contributed to the deterrence of a conventional conflict, but such escalation would have entailed enormous risks: once the nuclear threshold was crossed, where would matters stop? Many analysts question the ability to control escalation once nuclear weapons enter into use. As reported by Fred Kaplan in The Bomb, in 2017, Secretary of Defense Jim Mattis asked a group of senior Pentagon officials if they believed that nuclear war could be controlled; only one thought that it was possible. 

The Obama administration’s 2010 nuclear posture review sought to reduce the number and role of nuclear weapons in U.S. policy. The document stated that “the United States will not use or threaten to use nuclear weapons against non-nuclear weapons states that are party to the NPT [Non-Proliferation Treaty] and in compliance with their nuclear non-proliferation obligations.” If such a non-nuclear weapons state attacked America or an American ally or partner with conventional, chemical or biological weapons, this negative security assurance meant that the U.S. military response would not be nuclear. (The review did contain a footnote to the effect that developments in biological weapons might lead Washington to revisit the negative security assurance.)

The 2010 nuclear posture review also stated that the United States would resort to nuclear weapons only in extreme circumstances and that the “fundamental purpose” of U.S. nuclear arms was to deter a nuclear attack on America, its allies or its partners. That language left open the possibility of a nuclear response to a conventional attack by a nuclear weapons state or another country not covered by the negative security assurance. The review added that the United States would “continue to strengthen its conventional capabilities and reduce the role of nuclear weapons in deterring non-nuclear attacks” with the goal of making deterring nuclear attacks the sole purpose of the U.S. nuclear arsenal.

The Trump administration’s 2018 nuclear posture review reflected continuity with its predecessor in some ways but diverged in others. Instead of reducing the role of nuclear weapons and rejecting new nuclear weapons, the 2018 review called for new “supplemental” nuclear capabilities: a low-yield submarine-launched ballistic missile warhead and low-yield warhead for a sea-launched cruise missile. While reiterating that the United States would use nuclear weapons only in extreme circumstances, the review said that those circumstances included “significant non-nuclear strategic attacks” on U.S., allied and partner civilian populations, U.S. and allied nuclear forces, nuclear command and control systems, or warning and attack assessment capabilities. Many observers believed that the language broadened the circumstances for nuclear use, at least compared to Obama administration policy, particularly given President Donald Trump’s threats, some veiled and others more explicit, to use nuclear weapons. 

The Trump administration’s nuclear posture review did restate the Obama administration’s negative security assurance, though its version reserved an unnecessarily broader right to reconsider the assurance. (The Obama administration’s footnote, which focused solely on developments in the biological weapons field, is more appropriate.) 

Nuke a Nuclear Weapons State? 

The Obama/Trump negative security assurance covers 95 percent of the nations in the world. The possibility of the United States using nuclear weapons relates to just a handful of countries: nuclear weapons states and countries which Washington judges not to be in full compliance with their nuclear nonproliferation obligations (only Iran and Syria are thought of in this context). The countries of greatest relevance boil down to Russia, China and North Korea. 

Of the two major potential adversaries, China has long had a declared policy of no first use of nuclear arms, though some question whether Beijing would abide by this declaration in all scenarios. Russian declaratory policy states that Russia would resort to nuclear weapons only if nuclear or other weapons of mass destruction were used against Russia or a Russian ally, or if there were a conventional attack on Russia that put the existence of the state at stake. 

What scenarios might lead to U.S. consideration of nuclear first use? One could be a conventional NATO-Russia conflict in the Baltic region in which the Russian military attains or is on the verge of attaining victory given its regional advantages. NATO overall has more powerful conventional forces, but marshaling them would take time. In this scenario, would an American president really decide to launch a nuclear attack on Russian forces on a NATO member’s territory or Russia itself? He or she would have to weigh the high probability of nuclear retaliation, including against the U.S. homeland. The president almost certainly would set aside the nuclear option, opting for time to build up American and NATO conventional forces for a counter-offensive.

Another scenario could involve a conflict with China in which the Chinese military, using its large arsenal of conventionally-armed ballistic missiles, pushes back U.S. naval and air forces. How successful a Chinese offensive might be given the spectrum of U.S. conventional capabilities, perhaps augmented by those of U.S. allies, is unclear. However, going nuclear would mean striking China directly. Again, the president would have to consider the very real prospect that Beijing would respond with a nuclear attack against American military bases in the Pacific, such as Guam, or against the United States. Again, he or she almost certainly would look for conventional options, even if they would take time. 

The Trump administration’s nuclear posture review raised another scenario: a significant non-nuclear strategic attack. Say that Russia launched a cyber strike on the U.S. electric power network, bringing down most of the grid from Boston to Washington, DC. That could prove a calamity, but would a U.S. president conclude that using nuclear weapons against the attacker, and then absorbing a nuclear counter-attack, would improve the situation? No, he or she almost certainly would order conventional and cyber counter-strikes, especially if there was the slightest doubt about correctly attributing the attack—a real question in the murky cyber world. 

As for North Korea, if struck first by U.S. nuclear weapons in a conflict, is there any doubt that Kim Jong-un would strike back with his nuclear arms? 

Escalating a conflict by introducing the use of nuclear arms is a scary, if not terrifying, proposition. It entails opening a Pandora’s box of unpredictable and potentially catastrophic consequences—especially when U.S. nuclear weapons would be used against a country that could strike back with its own nuclear arms. 

A Declaratory Policy That Lacks Credibility 

Those opposed to the sole purpose argue that the current ambiguity about U.S. readiness to use nuclear weapons first contributes to the deterrence of adversaries and the assurance of allies. That is a serious argument, but it made far more sense during the Cold War when the choice that might confront U.S. and NATO leaders was to use nuclear weapons or lose the war. Maintaining that ambiguity carries risks. Given the prospect of nuclear escalation once any nuclear weapons are used, and the changes in conventional force balances over the past thirty years, the chance that an American president would choose to use nuclear weapons first is vanishingly small. In virtually every conceivable scenario, he or she would look for other options, since the likely nuclear retaliation for a first-use effort by the United States would inevitably turn a bad situation into something much worse. 

Does it make sense to continue a declaratory policy aimed at deterring adversaries and assuring allies and partners that, on serious examination, neither foes nor friends would find credible? As America’s allies and partners see the U.S. threat to use nuclear weapons first lacking credibility, that could undermine their confidence in the U.S. threat to use nuclear weapons in response to a nuclear attack on them. 

Eliminating the ambiguity by adopting the sole purpose might not provide a huge security bonus, but it would have a positive security impact. Russia likely would not follow, at least not in the near term. However, the change could help defuse the current situation, in which both Washington and Moscow believe that the other seeks to lower the nuclear threshold and thus is adjusting its own nuclear policy accordingly. It is not in the U.S. interest that the Russians believe America might go nuclear first and develop (or further develop) a posture to beat Washington to the nuclear punch. That fosters conditions that could be very dangerous in a conventional crisis or conflict and make nuclear use more likely.

Adopting the sole purpose would send an interesting signal to China. Some analysts question whether Beijing will continue to adhere to a no first use policy, but the Pentagon reports that “China almost certainly keeps the majority of its nuclear force on a peacetime status—with separated launchers, missiles, and warheads,” a posture consistent with that policy. Adoption of the sole purpose could open the path to a strategic security dialogue with Beijing that has eluded Washington for years. It would raise the political costs to China of abandoning its no first use posture. A change in American policy might even help avoid the development of a U.S.-China nuclear standoff somewhat similar to that between Washington and Moscow during the Cold War. 

The adoption of a sole-purpose policy would reduce the ability of a U.S. president to use nuclear weapons for saber-rattling. But giving up the option to rattle a saber that the adversary believes Washington would never draw seems to give up little.

A Nuclear Taboo?

It has been seventy-five years since the United States dropped two atomic bombs on Japan at the conclusion of World War II. Since then, neither America nor any other country has used nuclear arms in anger. Some suggest a taboo against nuclear use has developed. 

The taboo is informal, not fixed by international agreement. It would benefit U.S. and allied security were non-use of nuclear weapons to become a widely accepted and entrenched international norm. The United States has powerful conventional forces, favorable geography and the world’s largest network of allies, so reducing the possibility of nuclear use seems very much in the U.S. interest, reducing one of the few existential threats to America’s existence. Sole purpose would help bolster that norm.

Adopting sole purpose would mark a significant change in U.S. policy. Washington should do so only after consulting with NATO and key allies in the Pacific region. Importantly, the sole purpose would not close the U.S. nuclear umbrella; it would mean that U.S. nuclear weapons would be used in an ally’s defense only after the other side had gone nuclear. Unlike nuclear first use, the threat of nuclear retaliation after a nuclear attack is credible. 

The next U.S. nuclear posture review should, following such consultations, adopt sole purpose as the reason for U.S. nuclear weapons. That would change a dynamic that now has possible adversaries designing potentially dangerous policies and postures in a belief that the United States is lowering its threshold for use of nuclear weapons and could go nuclear first. It would boost the establishment of an international norm against any nuclear weapons use. It could help make Americans safer. And the only cost: abandoning an option that an American president would never use and whose threat has little credibility.

Steven Pifer is a William Perry Research Fellow at Stanford’s Center for International Security and Cooperation and a retired U.S. Foreign Service officer.

Originally for The National Interest

Watch the conversation at Bridging the Gap

The archival record makes clear that killing large numbers of civilians was the primary purpose of the atomic bombing of Hiroshima; destruction of military targets and war industry was a secondary goal and one that “legitimized” the intentional destruction of a city in the minds of some participants. The atomic bomb was detonated over the center of Hiroshima. More than 70,000 men, women, and children were killed immediately; the munitions factories on the periphery of the city were left largely unscathed. Such a nuclear attack would be illegal today. It would violate three major requirements of the law of armed conflict codified in Additional Protocol I of the Geneva Conventions: the principles of distinction, proportionality, and precaution. There could be great pressure to use nuclear weapons in future scenarios in which many American soldiers’ lives are at risk and there is no guarantee that a future US president would follow the law of armed conflict. That is why the United States needs senior military officers who fully understand the law and demand compliance and presidents who care about law and justice in war.

Read the rest at Bulletin of Atomic Scientists

Seventy-five years ago, before 5:30 a.m. on July 16, 1945, Los Alamos scientists successfully conducted the world’s first nuclear weapons test. The test, which physicist J. Robert Oppenheimer named "Trinity" after a line from a poem by John Donne, altered the course of World War II, changed the way scientific discoveries are pursued, and cemented the relationship between science and national security.

Siegfried Hecker, a senior fellow at Stanford’s Center for International Security and Cooperation, worked at Los Alamos National Laboratory for over three decades and served as director for nearly 12 of those years. He joined CISAC in 2005 and served as the Center’s Science Co-director from 2007 – 2012.

In a video produced by Los Alamos to commemorate the historic events of 1945, Hecker reflects on the meaning of that moment. Here, Hecker answers questions to place those events into context of today’s national security landscape and his current work.

As you say in the video, the Trinity project brought scientists from all over the world to Los Alamos and asked them to collaborate on the most sensitive project for the American government. At the time, that must have seemed radical, but did multidisciplinary, international collaboration become the norm?

 It may seem odd, but it would be more difficult today than it was then. The U.S. was at war and concerned about Hitler’s Germany winning the race to the atomic bomb. It was actually the Brits that tried to convince President Roosevelt to mount a major effort to build the bomb. It was Europe that was the center of great physics at the time and it was Hitler who caused many of the best scientists to flee Europe and come to the United States – we welcomed them with open arms. We had the industrial capacity to mount such an enormous enterprise and did not have the enemy at our doorstep. But we needed their scientific skills and could not have developed the bomb in 27 months without them. Unfortunately, today we have retreated to more of a bunker mentality and are not as welcoming as we were then. For that matter, we’re not as welcoming as we were in 1956, when America allowed me to immigrate from Austria.  

The scientists involved in this project had the agility to switch designs as they made new discoveries. Could you describe the type of talent and skills that allowed them to pursue new ideas so quickly?

Success of the Manhattan Project is typically viewed as the work of physicists. But it was really an incredible array of talent – spanning physics, chemistry, mathematics, computing, engineering, materials and others, that allowed it to deal with surprises like the gun-assembly not working with plutonium. That collaboration also allowed the team to redirect its energy when they found out that although plutonium may have been the physicist’s dream, it was an engineering nightmare. The metallurgists found a fix by adding a bit of gallium as I explain in the video. Understanding why that’s so occupied a good part of my scientific life at Los Alamos.

How does your time at Los Alamos National Laboratory relate to the work you do now with students and pre- and post-doctoral fellows at CISAC?

Once the Soviet Union dissolved at the end of 1991, I turned much of my attention to working with the Russian nuclear establishment to mitigate the new nuclear dangers resulting from the political chaos. My Russian nuclear colleagues and I captured twenty-plus years of collaboration in our book Doomed to Cooperate. It turned out that CISAC became a great place for me to continue this work in 2005 and to expand it to the other nuclear countries around the world. Once at Stanford, I found that one of the most rewarding things I could do was to teach and work with students and post-docs. That’s what I continue to do today in what we call Young Professionals Nuclear Forums. We bring together around a dozen young Americans to work with their counterparts in Russia on nuclear challenges. We do the same with Chinese and American young professionals.

Since its founding, CISAC has always had two directors—one with a science background and the other from the social sciences. As both a former director of CISAC and Los Alamos, can you explain how an academic center like CISAC, with that kind of combined leadership, can help to prepare the next generation of thinkers in international security?

That’s one of the things that attracted me to CISAC. From CISAC’s founding days of John Lewis (political science) and Sid Drell (physics), the Center has tackled problems at the intersection of the natural and social sciences. And, that’s where the hard problems lie. By focusing on the challenges that arise at this intersection, CISAC can help to educate the next generation of national security specialists to tackle the world’s difficult problems. It’s a great place to be if you are interested in international security.

Watch The Science of Trinity 

President Donald Trump’s chief arms control envoy last week acknowledged the possibility that the 2010 New Strategic Arms Reduction Treaty (New START) could be extended, but he added, “only under select circumstances.”  He then put down conditions that, if adhered to, will ensure the Trump administration does not extend the treaty.

New START and Extension

New START limits the United States and Russia each to no more than 700 deployed strategic missiles and bombers and no more than 1,550 deployed strategic warheads.  It expires by its terms on February 5, 2021 but can be extended for up to five years.  The Trump administration has adamantly refused to do that.

From the perspective of U.S. national security interests, extending New START is a no-brainer.  As confirmed by the State Department’s annual report, Russia is complying with the treaty’s limits.  Extension would keep Russian strategic forces constrained until 2026.  It would also ensure the continued flow of information about those forces produced by the treaty’s data exchanges, notifications, on-site inspections and other verification measures.

And extension would not force a single change in U.S. plans to modernize its strategic forces, as those plans were designed to fit within New START’s limits.

Russian officials, including Vladimir Putin, have raised New START extension since the first days of the Trump administration.  In 2017, Trump administration officials deferred on the issue, saying they would consider extension after (1) completion of a nuclear posture review and (2) seeing whether Russia met the treaty’s limits, which took full effect in February 2018.

Russia fully met the limits in February 2018.  At about the same time, the administration issued its nuclear posture review.  Yet, more than two years later, New START extension remains an open question.

On June 24, Amb. Marshall Billingslea, the president arms control envoy, briefed the press on his meeting with his Russian counterpart two days before in Vienna.  Asked about extending New START, Amb. Billingslea—never a fan of the treaty or, it seems, any arms control treaty—left the option open.  However, he described three conditions that will block extension.

China

Amb. Billingslea’s first condition focused on China, which he claimed had “an obligation to negotiate with [the United States] and Russia.”  Beijing certainly does not see it that way—saying no, no and again no—citing the huge disparity between the size of the Chinese nuclear arsenal and those of the United States and Russia.  China has less than one-tenth the number of nuclear warheads of each of the two nuclear superpowers.

To be sure, including China in the nuclear arms control process is desirable.  But Beijing will not join a negotiation aimed at a trilateral agreement.  What would such an agreement look like?  Neither Washington nor Moscow would agree to reduce to China’s level (about 300 nuclear warheads).  Nothing suggests either would agree to legitimize a Chinese build-up to match their levels (about 4,000 each).  Beijing presumably would not be interested in unequal limits.

This perhaps explains why, well more than one year after it began calling for China’s inclusion, the Trump administration appears to have no proposal or outline or even principles for a trilateral agreement.

For its part, Moscow would welcome China limiting its nuclear arms.  The Russians, however, choose not press the question, raising instead Britain and France.  Amb. Billingslea pooh-poohed the notion, but France has as many nuclear weapons as China, and Britain has two-thirds the Chinese number.  The logic for bringing in one but not the other two is unclear.  The question raises yet another hinderance to including China.

A more nuanced approach might prove more successful.  It would entail a new U.S.-Russian agreement providing for reductions beyond those mandated by New START.  Washington and Moscow could then ask the Chinese (and British and French) to provide transparency on their nuclear weapons numbers and agree not to increase their total weapons or exceed a specified number.  Much like his president, however, the arms control envoy does not appear to be into nuance.

Non-Strategic Nuclear Weapons

Amb. Billingslea’s second condition dealt with including in a new negotiation nuclear arms not constrained by New START, especially Russia’s large number of non-strategic nuclear weapons.  Again, this is laudable goal, but getting there will require much time and unpalatable decisions that the Trump administration will not want to face.

Russian officials have regularly tied their readiness to discuss non-strategic nuclear arms to issues of concern to them, particularly missile defense.  The Trump administration,  however, has made clear that it has zero interest in negotiating missile defense.

Even if Moscow severed that linkage, negotiating limits on non-strategic nuclear weapons would take time.  New START limits deployed strategic warheads by virtue of their association with deployed strategic missiles and bombers.  The only warheads directly counted are those on deployed intercontinental ballistic missiles and submarine-launched ballistic missiles.

By contrast, most if not all non-strategic warheads are not mounted on their delivery systems.  Monitoring any agreed limits would require new procedures, including for conducting on-site inspections within storage facilities.  This does not pose an insoluble challenge, but it represents new territory for both Washington and Moscow.  Working out limits, counting rules and verification measures will prove neither quick nor easy.

Verification

Amb. Billingslea earlier suggested some dissatisfaction with New START’s verification measures, though he did not articulate any particular flaw, and, as noted, the State Department’s annual compliance report says Russia is meeting the treaty’s terms.  Last week, he made verification measures for his desired U.S.-Russia-China agreement the third condition for New START extension. 

Verification measures are critical.  Treaty parties have to have confidence that all sides are observing the agreement’s limits or, at a minimum, that any militarily significant violation would be detected in time to take countervailing measures.  Working out agreement on those measures will prove a long process, even in just a bilateral negotiation, especially if it addresses issues such as stored nuclear weapons.  That is not just because of Russian reluctance to accept intrusive verification measures such as on-site inspection; the U.S. military also wants verification measures that do not greatly impact its normal operations.

Russian officials have reiterated their readiness to extend New START now.  Amb. Billingslea’s conditions will thwart extension for the foreseeable future.  That’s unfortunate.  By not extending New START, the Trump administration forgoes a simple action that would strengthen U.S. national security and make Americans safer.

Ending the moratorium would not advance U.S. security interests.  The United States has conducted about as many nuclear weapons tests as the rest of the world combined (and 30 percent more than the number conducted by the Soviet Union/Russia).  U.S. weapons scientists learned more from testing.  When I served as a diplomat at the American Embassy in Moscow in 1988, I accompanied a U.S. team to the Soviet nuclear test site at Semipalatinsk (in what is now Kazakhstan).  Our Soviet hosts showed us a vertical shaft for an upcoming underground test; it was about three feet in diameter.  A U.S. team member from the test site in Nevada, which the Soviets would visit the following month, commented that U.S.-drilled vertical shafts for nuclear tests typically were nine to eleven feet in diameter.  That maximized the area above the weapon for instruments that would gather a burst of data in the nanosecond before they vaporized.

The testing moratorium and the CTBT, if ratified and entered into force, would seem to lock in an area of U.S. advantage regarding nuclear weapons and nuclear effects.  Why would we want others to test and erode that advantage?

Up until the idea of gaining leverage with Beijing and Moscow arose, the primary possible reason for a return to testing was if it became necessary to confirm the reliability of a weapons type in the stockpile.  However, the National Nuclear Security Administration has overseen for 25 years the Stockpile Stewardship Program, intended to confirm that U.S. nuclear weapons are safe, secure and reliable without having to test them in a manner that produces a nuclear yield. To do so, the program uses supercomputers, modeling and tools such as the Dual Axis Radiographic Hydrodynamic Test Facility (think of the world’s most powerful X-ray device).

Each year, the commander of Strategic Command and the directors of the national nuclear laboratories at Los Alamos, Sandia and Lawrence Livermore certify the safety and reliability of the nuclear stockpile.  When I visited Los Alamos several years ago, the director told me that, as long as the Stockpile Stewardship Program was funded, he was confident that nuclear testing was not needed.  He added that, as a result of the program, weapons scientists had learned things about how nuclear weapons work that they did not and could not learn from testing nuclear weapons underground.

The smart thing for U.S. national interests is to continue the moratorium, ratify the CTBT, and press others to ratify so that the treaty can be brought into force.  The Senate failed to give consent to ratification in 1999, due to concerns about how to maintain the stockpile’s reliability without nuclear testing and about monitoring the treaty.  The Stockpile Stewardship Program, just in its beginning stage then, can now answer the first concern and has been doing so.

As for monitoring a test ban, U.S. national technical means have improved over the past two decades, and the Comprehensive Test Ban Treaty Organization has established the International Monitoring System with some 300 stations around the world.  It can detect underground nuclear explosions down to below one kiloton (the weapon that destroyed Hiroshima had a yield of 15 kilotons) as well as detecting tests in the atmosphere or ocean, both of which are banned by the 1963 Limited Test Ban Treaty.  Once in force, the CTBT also provides for an inspection mechanism.

As former Secretary of State George Shultz said in 2013, senators might have been correct not to consent to ratification in 1999, but given the Stockpile Stewardship Program’s development and enhanced monitoring systems, they would be right to vote for ratification now.

Conducting a nuclear test to bring China and Russia to the negotiating table will not work.  It will instead open the door for others to resume testing and close a nuclear weapons knowledge gap that favors the United States.  That will not make us safer or more secure.  It is an unwise idea that hopefully will continue to meet resistance within the U.S. government.