A Russian Yars RS-24 intercontinental ballistic missile system parades through Red Square during a rehearsal of the Victory Day military parade in Moscow on May 6, 2018.

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Russian President Vladimir Putin’s announcement Tuesday that Russia would suspend participation in the New START treaty, a key nuclear arms reduction agreement, is the latest in a series of ominous declarations in which he has made reference to his nuclear arsenal.

What specifically this latest move will mean in terms of the worldwide nuclear threat is something of a question mark.

The treaty was already essentially paused since Russia had recently refused to open up its arsenal to inspectors.

CNN’s report notes that Putin is not technically withdrawing from the treaty, so his declaration “appears to be formalizing its current position.”

Russia’s Foreign Ministry later clarified that Moscow will continue to respect the caps established in the treaty and that Putin’s suspension of the treaty is “reversible.”

What is New START?

New START – “START” is shorthand for “Strategic Arms Reduction Treaty” – is the last in a long series of nuclear treaties between the US and Russia, previously the Soviet Union.

Strategic nuclear weapons are larger warheads that could wipe away cities. Russia and the US both also have smaller “tactical” nuclear weapons not covered by the New START treaty. Much less is known about Russia’s arsenal of tactical nuclear weapons. Read more about Russia and tactical nuclear weapons.

President Barack Obama laughs with his Russian counterpart Dmitry Medvedev as they sign the New START treaty in Prague on April 8, 2010.

First signed during the Obama administration to take effect in 2011 and then renewed in February 2021, shortly after President Joe Biden took office, the strategic arms treaty places a cap on the number nuclear armaments each country can have.

What are the caps on ‘strategic’ nuclear weapons?

The caps, as described by the US State Department, are:

  • 700 deployed intercontinental ballistic missiles (ICBMs), deployed submarine-launched ballistic missiles (SLBMs), and deployed heavy bombers equipped for nuclear armaments;
  • 1,550 nuclear warheads on deployed ICBMs, deployed SLBMs, and deployed heavy bombers equipped for nuclear armaments (each such heavy bomber is counted as one warhead toward this limit);
  • 800 deployed and non-deployed ICBM launchers, SLBM launchers, and heavy bombers equipped for nuclear armaments.

The current extension lasts until February 2026, but both countries have complained about the other’s compliance.

In January, the US accused Russia of, among other things, continuing to refuse to allow inspections of its nuclear facilities, a key verification condition on the treaty.

Russia has raised questions about US claims it converted some previously nuclear-capable bombers to only carry conventional weapons.

Here’s a 60-page Congressional Research Service report on debates around New START.

Generally speaking, recent Democratic administrations have pursued treaties like this and recent Republican administrations have questioned their utility. President George W. Bush withdrew the US from an Anti-Ballistic Missile Treaty, and President Donald Trump withdrew the US from the Intermediate-Range Nuclear Forces Treaty. Presidents Barack Obama and Biden both endorsed New START.

What will happen now?

I went back to the authors of the 2017 book, “Nuclear Weapons and Coercive Diplomacy” – Matthew Fuhrmann, a professor at Texas A&M University, and Todd Sechser, a professor at the University of Virginia – for their assessment of what this new development means in terms of worldwide nuclear security.

I’ve spoken to them periodically over the past year about Putin’s nuclear rhetoric. I asked Sechser some specific questions and Fuhrmann offered some general thoughts about what Putin’s move means. Portions of both conversations are below.

This feels like a form of retaliation

FUHRMANN: Putin’s announcement strikes me as retaliation for increased US support for Ukraine, including Joe Biden’s recent visit to Kyiv. Russian leaders seem to believe that the US is now more determined to reverse its invasion of Ukraine, trying to facilitate what they would see as a strategic defeat.

However, Putin’s announcement on New START formalizes much of what Russia was already doing. The treaty requires reciprocal inspections to verify compliance, but Russia has not allowed this to happen since last fall, when they were supposed to resume following the Covid pandemic.

Based on this, Washington had already accused Russia of being in noncompliance with the treaty.

More symbolism than substance

WOLF: Does Putin’s announcement materially change the nuclear situation?

SECHSER: In the short run, the impact of this announcement is more symbolism than substance. Russia already announced six months ago that it would no longer allow inspections of its nuclear arsenal. And it is not going to suddenly build a massive new arsenal tomorrow.

But the symbolism is important: This is the last remaining nuclear arms control treaty between the United States and Russia. In the long run, the deterioration of US-Russian relations, along with the demise of this treaty, provide both motive and opportunity for a new nuclear arms race.

US support for Ukraine has evolved in important ways

WOLF: Many of the guardrails the US had put on its support for Ukraine in the hopes of not threatening Russia within its borders – not sending certain offensive weapons like longer-range missiles – have been abandoned as the war has progressed. Now there is serious talk of supplying F-16s. Have the US and the West gone too far in arming Ukraine? Should they go further?

SECHSER: I am struck by how careful the Biden administration has been with its military assistance, even going so far as to modify weapons systems so Ukraine could not use them to launch long-range attacks into Russia. It has provided increasingly sophisticated weapons, but only gradually.

In a way, Putin’s announcement about New START can be seen as a validation of this careful strategy because of what it is not: namely, a massive military response against the West.

Only Putin knows where his red lines are, but this announcement suggests that the United States has not yet crossed them.

Putin’s nuclear threats have failed so far

WOLF: One year into the war – and about a year after we first talked – I wonder what you think people should know about how the nuclear threat has evolved.

SECHSER: It is hard to ignore just how little Putin’s nuclear threats have accomplished. After a year of bluster about Russia using “all available means” against its enemies, the Ukrainians have not budged and the West is increasing its commitment to Ukraine, not shrinking away.

If anything, Putin’s nuclear bellicosity has only fueled the international backlash against Russia. Russia’s experience over the past year offers a vivid reminder that nuclear weapons are not a magic wand.

A new era of arms control

WOLF: This is the last remaining treaty on nuclear weapons between the US and Russia. Is the era of nonproliferation essentially over?

SECHSER: US-Russian arms control has been on a downward spiral for a long time. This is the fourth US-Russian arms control treaty to come to an end during Putin’s regime.

The extension of New START two years ago was a cautiously optimistic sign, but the invasion of Ukraine erased that progress. This announcement is really the culmination of more than a decade of gradual erosion. It is hard to see a future for US-Russian arms control as long as Putin remains in power.

Probability of Russia using nuclear weapons remains low

FUHRMANN: The potential for nuclear escalation increases as the situation in Ukraine worsens for Russia. The overall probability of Russian nuclear use remains low, in my opinion, but it will increase if desperation sets in for Russia. (Former Russian President Dmitry) Medvedev wrote recently, “Nuclear powers do not lose major conflicts on which their fate depends.”

Nuclear-armed countries have ended wars in the past on less than favorable terms without using nuclear weapons. Examples include the US experiences in Korea and Vietnam, as well as the Soviet war in Afghanistan from 1979 to 1989.

The question becomes whether Russian leaders see the stakes in Ukraine as sufficiently vital to justify using tactical nuclear weapons – an action that would be tremendously costly for Russia and potentially Putin himself.