A Russian official warned on Friday of an "uncontrollable" arms race involving multiple nuclear powers, the state-owned RIA news agency said.
"In essence, we are witnessing a missile arms race with consequences that are hard to predict. Tens of billions of dollars are being invested in improving missile technology. This process is taking on an uncontrollable character," Grigory Mashkov, ambassador-at-large, was quoted as saying.
RIA said Mashkov referred in a magazine interview to China's rapid expansion of its missile systems and to the nuclear capabilities of Israel, India and Pakistan.
Atomic scientists said in January that the "Doomsday Clock" - a notional measure of the risk of mankind's extinction - had ticked closer to midnight than ever before as a result of rising nuclear tensions since Russia's invasion of Ukraine.
Russia has claimed four regions of Ukraine as its own territory and placed them under its nuclear umbrella, in moves condemned as illegal by most countries at the United Nations. President Vladimir Putin has said repeatedly that Russia would use all means at its disposal to defend its "territorial integrity".
In February, Putin announced Moscow was suspending the New START treaty with the United States, which limits each side's deployed nuclear warheads, saying Washington was trying to inflict a "strategic defeat" on Russia in Ukraine.
Earlier, RIA quoted the Russian Foreign Ministry as saying a "vacuum" could arise in strategic stability once New START expires in 2026. It was not clear whether this was a ministry statement or a comment from Mashkov's interview.
RIA also quoted the ministry as saying Moscow needed to build up its tactical missile capabilities including in its Kaliningrad region, which borders NATO members Poland and Lithuania.
(Reporting by Reuters, writing by Mark Trevelyan; Editing by Gareth Jones)