Russian Deputy Foreign Minister Sergei Ryabkov said on Monday the United States could face "fatal consequences" if it ignored Moscow's warnings not to let Ukraine use weapons provided by Washington to strike targets inside Russia.
Ryabkov was commenting on President Joe Biden's decision last week to approve the use of US-supplied weapons to hit targets inside Russia that were involved in attacks on Ukraine's Kharkiv region.
"I would like to warn American leaders against miscalculations that could have fatal consequences. For unknown reasons, they underestimate the seriousness of the rebuff they may receive," state news agency RIA quoted Ryabkov as saying.
He referred to comments last week by President Vladimir Putin, who said NATO countries were playing with fire and risking a deeper global conflict - one of a series of warnings from Moscow about the risk of a serious escalation.
"I urge these figures (in the US) ... to spend some of their time, which they apparently spend on some kind of video games, judging by the lightness of their approach, on studying what was said in detail by Putin," Ryabkov said.
Putin had delivered "a very significant warning and it must be taken with the utmost seriousness”, he added.
Putin said the West would be directly involved in any use of its weapons by Ukraine to strike deep inside Russia, because such attacks would require its satellite, intelligence and military help.
NATO Secretary General Jens Stoltenberg said last week that NATO had the right to help Ukraine uphold its own right to self-defense, and this did not make NATO a party to the conflict.
Ukrainian President Volodymyr Zelenskiy said at the weekend that Kyiv was grateful to Washington for allowing it to use US-supplied HIMARS rocket systems in the Kharkiv region, but this was not enough. Ukraine has long argued that restrictions on the way it can use Western-supplied weapons are seriously limiting its ability to defend itself.
Russian news agencies quoted Ryabkov as saying that attempts by Kyiv to attack Russian early-warning radar systems would be thwarted and Moscow may respond asymmetrically to such steps.
A Kyiv intelligence source said last week that a Ukrainian drone had targeted a long-range radar deep inside Russia that is part of Russia's early-warning system to detect whether it is under nuclear attack.
