Deputy Foreign Minister Sergei Ryabkov told Russian news agencies on Wednesday that Moscow had halted all information exchanges with Washington after suspending its participation in the New START nuclear arms treaty last month.

“There will be no notifications at all,” Ryabkov said in remarks reported by Russian news agencies when asked if Moscow would also stop issuing notices about planned missile tests.

“All notifications, all kinds of notifications, all activities within the framework of the treaty will be suspended and will not be conducted regardless of what position the US may take,” he said.

The US said on Tuesday that it would cease providing Moscow with detailed data on its nuclear weapons stockpiles in response to Russia’s suspension of participation in New START.

“Russia has not been in full compliance and refused to share data which we … agreed in New START to share biannually,” John Kirby, the US National Security Council spokesperson said. “Since they have refused to be in compliance … we have decided to likewise not share that data,” he said.

A semi-annual exchange of information between Russia and the US on such issues as their number of nuclear warheads and nuclear-capable bombers on certain bases had been an important measure of the New START treaty.

Last month, President Vladimir Putin suspended Russia’s participation in the treaty, saying Moscow could not accept US inspections of its nuclear sites under the agreement when Washington and its NATO allies have openly declared Moscow’s defeat in Ukraine as their goal.

Moscow emphasised that it had not withdrawn from the START pact altogether and would continue to respect the caps on nuclear weapons the treaty sets. Russia’s foreign ministry had also said that Moscow would keep notifying the US about planned test launches of its ballistic missiles – a key agreement between Washington and Moscow.

Both countries have exchanged notifications about test launches of their ballistic missiles since the Cold War era. Russia’s foreign ministry said last month that Moscow will keep issuing them in line with a 1988 agreement between the US and Soviet Union.

Speculation that Ryabkov’s comments on Wednesday might also refer to Russia’s suspension of information on ballistic missile launches – a hugely provocative move – under the 1988 agreement was quickly discounted.

Pavel Podvig, an expert on Russian nuclear forces, tweeted that Ryabkov’s reference to the termination of notices in the context of New START indicated that Russia will keep issuing them in conformity with the 1988 pact.

Regarding those launch notifications. Here is what Ryabkov actually said: “all types of activities IN THE FRAMEWORK OF THE TREATY.” https://t.co/wJ1yUIlEvd In the treaty. Launch notifications are covered by the 1988 agreement. Which (see next tweet) Russia said it will keep 1/2 pic.twitter.com/5UZPQc0PbP

— Pavel Podvig (@russianforces) March 29, 2023

Strategic stability

Notices on ballistic launches under the 1988 agreement have been an essential element of strategic stability for decades, allowing Russia and the US to correctly interpret each other’s moves and make sure neither country mistakes a test launch for a missile attack.

The New START treaty, signed in 2010 by then-Presidents Barack Obama and Dmitry Medvedev, limits each country to no more than 1,550 deployed nuclear warheads and 700 deployed missiles and bombers. The agreement envisages sweeping on-site inspections to verify compliance.

On Wednesday, Russia’s defence ministry said drills had started with the country’s Yars mobile ICBM launchers – considered the backbone of Russia’s strategic missile forces – and involved manoeuvres across three regions of Siberia.

The exercises involve measures to conceal the deployment of Yars from foreign satellites and other intelligence assets, the ministry said.

The defence ministry did not say how long the drills would last or mention plans for any practice launches. The Yars ICBM has a range of about 11,000km (6,835 miles).

A defence ministry video shows trucks carrying the missiles driving from a base to go on patrol. The exercises involve about 300 vehicles and 3,000 troops in eastern Siberia, according to the ministry.

Russian officials have issued a barrage of hawkish statements since their troops entered Ukraine, warning that the continuing Western support for Kyiv raised the threat of a nuclear conflict.

In remarks published Tuesday, Nikolai Patrushev, the secretary of Russia’s Security Council, which Putin chairs, sternly warned the US and its allies against harbouring hopes for Russia’s defeat in Ukraine.

“Russia is patient and isn’t trying to scare anyone with its military superiority but it has unique modern weapons capable of destroying any adversary, including the United States, in case of a threat to its existence,” Patrushev said.