President Vladimir Putin said on Tuesday that Russia was suspending its participation in the New START treaty with the United States that limits the two sides' strategic nuclear arsenals.
Putin stressed that Russia was not withdrawing from the treaty but the suspension further imperils the last remaining pillar of arms control between the United States and Russia, which between them hold nearly 90% of the world's nuclear warheads - enough to destroy the planet many times over.
"In this regard, I am forced to announce today that Russia is suspending its participation in the strategic offensive arms treaty," Putin told lawmakers towards the end of a major speech to parliament, nearly one year into the war in Ukraine.
Putin said Russia's nuclear energy company Rosatom must also ensure the country's readiness to test a nuclear weapon if needed.
"Of course, we will not be the first to do this. But if the United States tests, then we will," he said. "No one must be under any dangerous illusions that global strategic parity can be destroyed."
The New START treaty was signed in Prague in 2010, came into force the following year, and was extended in 2021 for five more years just after U.S. President Joe Biden took office.
It caps the number of strategic nuclear warheads that the United States and Russia can deploy and the deployment of land- and submarine-based missiles and bombers to deliver them.
Experts say that Russia has the world's largest stockpile of nuclear weapons, with close to 6,000 warheads.