New START – the final ‘nuclear barrier’ of the US – Russia

For decades, the United States and Russia, the two countries possessing the world’s largest nuclear arsenals, have been bound by a series of control treaties to ensure that a nuclear disaster that could wipe out humanity does not occur. But this began to change on February 5, when the last remaining nuclear arms limitation treaty between the US and Russia, also known as New START, expired.

During the early decades of the Cold War, the United States and the Soviet Union raced to build nuclear arsenals, raising fears of a war of total destruction that could wipe out humanity. To prevent this risk, in the late 1960s, US President Lyndon Johnson called for negotiations with Moscow to limit the number of strategic weapons of each side.

Strategic Arms Limitation Negotiations (SALT) began under Johnson’s successor, President Richard Nixon, in Finland in 1969. In 1972, Nixon and Soviet leader Leonid Brezhnev signed a ballistic missile defense treaty and an agreement to limit the construction of temporary intercontinental ballistic missile (ICBM) stocks.

Under the subsequent START I and SORT agreements, the United States and the Soviet Union, followed by Russia, significantly reduced their nuclear arsenals. But arms control negotiations are often difficult and other draft treaties are never implemented.

In 2002, President George W. Bush’s administration unilaterally withdrew from the Anti-Ballistic Missile Treaty on the grounds that it limited America’s ability to defend itself against “terrorists” and “rogue states”.

To prevent the risk of miscalculation, in 2010, President Barack Obama and Russian President Dmitry Medvedev signed the New Strategic Arms Reduction Treaty (New START). The treaty took effect a year later, beginning the process of the United States and Russia shrinking their strategic offensive arsenals.

The agreement is separate from the Nuclear Non-Proliferation Treaty (NPT), which 191 countries including the US, Russia and all NATO members have joined since it entered into force in 1970.

New START has a term of 10 years and allows for a one-time extension of five years, which was done under President Joe Biden’s administration in 2021. It sets limits on strategic nuclear weapons, which each side would use to attack the other’s key political, military and industrial centers in the event of a nuclear war.

The treaty stipulates that each country must not deploy more than 700 ICBM missiles, submarine-launched ballistic missiles (SLBMs) ​​and bombers carrying nuclear weapons, as well as no more than 1,550 nuclear warheads on these vehicles. In addition, the number of “deployed or non-deployed” launchers per country cannot exceed 800.

The treaty also limits Russia’s long-range nuclear weapons from reaching US territory.

New START includes an on-site inspection mechanism, with short advance notice so that parties can confirm whether partners are complying with the agreement or not. According to regulations, each side can conduct 18 inspections per year, although this activity has not taken place in the past few years.

Although it still allows both the US and Russia to possess hundreds of nuclear weapons with great destructive power, New START has helped the two superpowers not continue the arms race. Over the years that followed, both countries complied with the treaty’s restrictions and maintained nuclear warhead numbers at or below prescribed levels.

However, during his first term, President Donald Trump called the treaty “seriously flawed” because it did not include shorter-range nuclear weapons, also known as tactical nuclear weapons. Negotiations to extend the treaty stalled under Trump, and his administration withdrew from another intermediate-range missile ban agreement with Russia.

New START discussions collapsed after Russian President Vladimir Putin launched a campaign in Ukraine in 2022. The following year, Putin suspended Russia’s participation in the treaty, citing US support for Ukraine in the war.

As a result, Russia stopped providing data and notifications as required by the treaty, while the US responded by doing the same, the US State Department said in a report to Congress in January 2025.

Although Russia’s suspension “has significantly weakened the treaty’s verification mechanism and reduced its effectiveness,” both countries continue to comply with the limits on the number of nuclear warheads under New START, according to Georgia Cole, a fellow at Britain’s Chatham House foreign policy institute.

“This shows that even when weakened, New START still strengthens strategic stability,” she added.

Russia said in September 2025 that it was willing to continue to comply with the core provisions of the treaty for at least the next year, if the United States did the same.

At the time, President Trump said the proposal “seemed like a good idea to me,” but the Kremlin said earlier this week it had not received an official response.

In the US, opinions on whether Mr. Trump should accept this proposal or not are divided. Supporters say it would demonstrate political will to avoid an arms race and give more time to figure out a way forward.

Rose Gottemoeller, who served as the head of the US treaty negotiation team, said that accepting Mr. Putin’s voluntary extension offer was an “obvious” decision. She warned that the US could fall into a weak position if the two countries race to increase nuclear warheads. “Russia can add warheads faster than us,” she said.

On the contrary, the opposition believes that the US should escape the constraints of New START to be able to increase its arsenal, especially in the context that other powers such as China are rapidly expanding their nuclear capabilities. They added that continued compliance with New START with Russia would send a signal of weakness.

In an interview with New York Times In early January, Mr. Trump said that if New START expires, “let it expire. We will make a better deal.” He complained that the deal had unresolved “weaknesses”.

Last year, Mr. Trump instructed the Pentagon to resume nuclear testing to “be on par” with Russia and China. However, it is unclear whether he meant nuclear explosions or just testing weapons capable of carrying nuclear warheads.

The expiration of the last nuclear treaty between the US and Russia has many people worried. The expiration of New START will create a large gap in efforts to limit and control the world’s two largest nuclear arsenals, because there are currently no negotiations on a successor treaty.

“This will increase the risk of miscalculation, incidents and unintended escalation, especially if a crisis occurs,” Ms Cole said.

This expert also warned that although Mr. Trump has suggested that he can reach a new agreement, “negotiating a treaty to replace New START in the current geopolitical context will be extremely difficult.”