The last nuclear arms control treaty between the United States and Russia, New START, signed in 2010, expires on Thursday.
Here’s what the treaty says and what its expiry means for Washington and Moscow.
What is New START?
START stands for Strategic Arms Reduction Treaty. The agreement is a 10-year agreement signed in 2010 by then-US President Barack Obama and Dmitry Medvedev, a close ally of Vladimir Putin who served one term as Russian president from 2008 to 2012, and entered into force in 2011.
New START was an extension of the previous treaty. START I, which reduces the number of strategic warheads deployed by both the United States and Russia, was signed between the United States and the Soviet Union in 1991 at the end of the Cold War and was in effect until 2009. START II was signed in 1993 with the aim of further reducing the number of deployed strategic nuclear warheads and completely eliminating multi-warhead intercontinental ballistic missiles, but it never went into effect. Russia officially left the EU in 2002.
From 2003 to 2011, the Strategic Offensive Reduction Treaty (SORT) also entered into force. Reductions in operationally deployed strategic warheads were required by both sides, but included minimal checks that relied on START I’s surveillance mechanisms. It was replaced in 2011 by New START.
New START was extended for another five years in 2021 after US President Joe Biden took office. The treaty stipulates that it can only be extended once.
The treaty limits the deployment of strategic nuclear weapons intended to attack key political, military, or industrial centers of enemy states.
Deployed weapons or warheads are in active service and ready for immediate use, as opposed to those in storage or awaiting dismantling.
Under this agreement, Moscow and Washington commit to:
It deploys fewer than 1,550 strategic nuclear warheads and up to 700 long-range missiles and bombers. Limit the deployment of intercontinental ballistic missiles to 800. Authorizes the other side to conduct up to 18 inspections of its strategic nuclear weapons facilities per year to ensure that the other side is not violating treaty limits.
The treaty allowed each country to send inspectors to each other’s nuclear facilities with little advance warning.
These tests were postponed to March 2020 due to the coronavirus disease (COVID-19) pandemic. Testing was not resumed after that.
In 2022, Russia began a full-scale invasion of Ukraine, and the war continued for four years.
Then, in 2023, Russian President Vladimir Putin suspended Moscow’s participation in the New START Treaty, citing Washington’s support for Ukraine during the war.
This meant that although Russia stopped participating in inspections and sharing data, it remained a party to the treaty.
This ended on-site inspections and left both countries relying on their own information to determine the other country’s compliance status. Nevertheless, neither side claims that the other has violated warhead limits, which remain in effect.
Why are treaties important?
The United States and Russia are the world’s largest nuclear powers in terms of the number of nuclear warheads they possess. Together, the United States and Russia possess about 90 percent of the world’s nuclear warheads.
The Center for Arms Control and Nonproliferation (CACNP) estimates that Moscow currently has 5,459 nuclear warheads, 1,600 of which are actively deployed.
According to CACNP, the United States has approximately 5,550 nuclear warheads, of which approximately 3,800 are in operation. At its peak in the mid-1960s during the Cold War, the U.S. stockpile consisted of more than 31,000 active and inactive nuclear warheads.
What did Trump say?
US President Donald Trump appears keen on a new agreement to limit nuclear weapons.
In an interview with The New York Times in January, President Trump said of the New START agreement, “When it expires, it expires. … We’re just going to get a better deal.”
President Trump also said he wants to involve China in nuclear talks. “We’re talking about limiting nuclear weapons, and we’re going to involve China in that,” President Trump said in August.
Separately, in the same month, prior to a meeting with South Korean President Lee Jae-myung, President Trump said, “I think denuclearization is a very big goal, but Russia is also keen on that, and I think China is too. We can’t allow the proliferation of nuclear weapons. We have to stop nuclear weapons. Their power is too strong.”
What did Moscow say?
Medvedev, who is currently deputy chairman of Russia’s Security Council, warned that the expiration of the New START treaty would mean the largest nuclear powers could expand their nuclear programs unrestricted for the first time since the 1970s.
“I don’t want to say that this immediately means the beginning of a catastrophe and a nuclear war, but everyone should still be on guard,” Medvedev said in an interview Monday from his home on the outskirts of Moscow. This was reported by Reuters, TASS, and Russian war blogger WarGonzo.
In September, President Putin proposed that the two countries should continue to abide by warhead limits for another year without a formal agreement.
“In order to avoid provoking a further strategic arms race and to ensure an acceptable level of predictability and restraint, I think it is justified to try to maintain the status quo established by the New START Treaty during the current rather turbulent period,” Putin said in a televised address from the Kremlin.
The Trump administration has not formally responded to the proposal.
But Putin has at times appeared more relaxed about the treaty. In October, he told reporters that Russia was developing new strategic weapons. It does not matter to Russia that the United States refuses to extend the warhead limits set out in New START.
He told reporters at the time: “Will these months be enough to decide on an extension? I think the goodwill to extend these agreements is enough. And if the American people decide they don’t need it, that’s not a big deal for us.”
What does the expiration of this treaty mean?
Once the treaty expires, there will be no legal limits on the number of deployable strategic nuclear warheads that the United States and Russia can each possess.
Writing for Chatham House, a London-based think tank, Georgia Cole, a fellow in the International Security Programme, wrote in late January: “This would represent a major rift in more than 50 years of bilateral nuclear arms control. It would also signal a departure from nuclear restraint and make the world a more dangerous place.”
Proponents of nuclear arms control have expressed concern that this could lead to the proliferation of nuclear warheads.
“Unless Trump and Putin reach some kind of agreement soon, it’s not unlikely that Russia and the United States will start putting more warheads on their missiles,” Darryl Kimball, executive director of the Arms Control Association, told Politico.
“Without New START restrictions, each side’s strategic plans are likely to be driven by uncertainty and worst-case assessments. This increases the risk of a new arms race, especially if either side begins adding warheads to existing missiles or expanding its delivery systems,” Cole wrote.
The US political news website also reported that the Pentagon is already planning for a future without the New START treaty, citing three anonymous sources familiar with the matter. It is unclear what these discussions and plans mean.
The United States and Russia have ramped up weapons production in recent years, developing nuclear-capable weapons designed to carry nuclear warheads, if not always.
In January, Russia attacked targets in western Ukraine near the Polish border with its nuclear-capable hypersonic missile Oreshnik. The missile was not equipped with a nuclear warhead, and it is unclear what kind of damage it caused to Ukraine.
