Russia's parliament suspended Moscow's participation in the New START treaty and officials blamed the US and the West for the breakdown of the pact. The move followed Russian President Vladimir Putin's announcement on Tuesday, while US President Joe Biden pledged his support for Ukraine. The New START treaty limits the number of deployed strategic nuclear warheads that the US and Russia can possess. The treaty was extended for five years in January 2021 after both sides agreed, but tensions have remained high. The move raises concerns about the future of arms control and a new arms race.