Following the inconclusive round of high-stakes talks between senior U.S. and Russian officials on nuclear arms control, European security, and the crisis in Ukraine last week, a journalist asked National Security Advisor Jake Sullivan on Jan. 13, “Are all options on the table?”

Sullivan replied that if Russia further invaded Ukraine, options that would be employed include severe sanctions on Russia and military aid for Ukraine, as well as “changes in the forces and capabilities that the United States and NATO would deploy to eastern flank allies to reinforce and strengthen the robustness of allied defense on allied territory.”

But the mere fact that the “all options on the table” question is being raised should be cause for great concern.

In the nuclear age, “all options on the table” in a conflict involving nuclear powers could be understood to mean the potential use of nuclear weapons, even if that wasn’t the intention in this instance. U.S. and Russian leaders must consider the use of such weapons off the table — there are no winners in a nuclear war.

Once nuclear weapons are used in a conflict involving nuclear-armed adversaries, even on a so-called “limited scale” involving a handful of “smaller” Hiroshima-sized bombs, there is no guarantee the conflict would not escalate and become a global nuclear conflagration. On the subject of escalation control, Air Force General John Hyten, the head of U.S. Strategic Command, said in 2018 after the annual Global Thunder wargame: “It ends bad. And the bad meaning it ends with global nuclear war.”

The Biden administration, to its credit, has said explicitly that its response to a possible Russian invasion of Ukraine will not involve direct U.S. or NATO military action. And, despite Russia’s very worrisome military buildup along its border with Ukraine, Russian leaders claim they have no intention to further invade.

Presidents Joe Biden and Vladimir Putin and the leaders of nuclear-armed Britain, France, and China issued a joint statement on Jan. 3 declaring their view that “a nuclear war cannot be won and must never be fought” –- a statement endorsed in 1985 by Presidents Ronald Reagan and Mikhail Gorbachev.

Unfortunately, the leaders of the nuclear five also said, ominously, that “nuclear weapons — for as long as they continue to exist — should serve defensive purposes, deter aggression, and prevent war.” Such broad language suggests they might consider the use of nuclear weapons to “defend” themselves against a wide range of threats, including non-nuclear threats.

The current crisis may, if mishandled, not only lead to a much wider, devastating, and protracted war between Russian and Ukrainian forces, but it could lead to an even more severe, if unintentional, escalatory spiral involving NATO and Russian forces, both of which have nuclear weapons at their disposal.

We should not need to remind ourselves of the terrible danger that these weapons pose, but, clearly, we do. If our leaders truly understood this danger, they could not possibly engage in the kind of nuclear saber rattling that we have seen in recent years.

The indiscriminate and horrific effects of nuclear weapons use are well-established. The vast majority of the world’s nations consider policies that threaten nuclear use to be dangerous, immoral, and legally unjustifiable.

In 1985, the organization International Physicians for the Prevention of Nuclear War won the Nobel Peace Prize for its work alerting the world to the catastrophic medical consequences that would result from nuclear war between the United States and the Soviet Union. (Co-author Ira is a co-founder and immediate past president of the group.) It should shock us all that, 30 years after the end of the Cold War, it is necessary to update that warning.

In 2020, researchers at Princeton’s Program on Science and Global Security published an estimate of what might happen if Russian or NATO leaders chose to use nuclear weapons first in a conflict in Europe. The result could be a quick escalation from a local disaster into a European nuclear war, and then a global catastrophe. Millions, perhaps tens of millions, would die in the first 45 minutes.

A detailed study published in 2002 assessed the direct consequences of a post-Cold War nuclear conflict between the United and Russia. It concluded that if 350 of the strategic nuclear warheads in the Russian arsenal (of approximately 1,450 total today) reached major industrial/military targets in the United States, 70 to 100 million people would die in the first hours from the explosions and fires. The U.S. president could quickly retaliate with as many as 1,350 nuclear weapons on long range missiles and bombers, and about 160 on shorter-range fighter-bombers based in Europe.

Many more people would be exposed to lethal doses of radiation. The entire economic infrastructure of the country would be destroyed — the internet, the electric grid, the food distribution system, the health system, the banking system, the transportation network. In the following weeks and months, the vast majority of those who did not die in the initial attack would succumb to starvation, exposure, radiation poisoning, and epidemic disease. A U.S. counterattack would cause the same level of destruction in Russia, and if NATO were involved in the war, Canada and Europe would suffer a similar fate.

More recent scientific studies indicate that the dust and soot produced by a nuclear exchange of 100-200 detonations would create lasting and potentially catastrophic climactic effects that would devastate food production and lead to famine in many parts of the world.

To defuse the current crisis in Ukraine and to address broader Russian and European security concerns, it is imperative for the two sides to negotiate an agreement to scale back large military exercises and avoid close military encounters between Russian and NATO forces, and, in the wake of the collapse of the Intermediate-Range Nuclear Forces Treaty, reach a deal to not deploy intermediate-range missiles in Europe or in Western Russia. Russia’s written proposals on these issues are not balanced, but provide a basis for talks, and Washington should take the initiative and offer workable, balanced counterproposals.

Progress through diplomacy in these areas would reduce tensions, build trust, and improve the climate for talks to address broader European security challenges.

The United States and Russia also need to conclude new agreements that achieve further verifiable cuts in strategic and nonstrategic nuclear forces and on constraints on long-range missile defenses by 2025, before the only remaining treaty limiting the world’s two largest arsenals (New START) expires in early 2026. Otherwise, leaders in Moscow and Washington will likely build up their deadly nuclear and missile stockpiles even further and make the next showdown between Russia and the West even more risky.

In the nuclear age, the U.S. and Russian leaders have a special responsibility to avert military conflict and to reduce the threats posed by nuclear weapons. Failure in not an option.

IMAGE: White House National Security Advisor Jake Sullivan calls on reporters while taking questions about President Joe Biden’s conversation with Russian President Vladimir Putin in the Brady Press Briefing Room at the White House on December 07, 2021 in Washington, DC. Sullivan reported that the conversation focused on Nordstream2 pipeline and the Russian military buildup near its border with Ukraine. Biden said the United States is prepared with economic penalties if Russia does invade. (Photo by Chip Somodevilla/Getty Images)