Russian President Vladimir Putin said a move by the West to allow Kiev to use longer-range weapons against targets inside Russia would mean NATO would be "at war" with Moscow.
Putin spoke about this while high-ranking diplomats of the USA and Great Britain discussed easing the rules for firing Western weapons at Russia, which Kiev insists on, more than two and a half years after the beginning of Russian aggression, writes the British newspaper The Guardian.
"This would significantly change the very nature of the conflict," Putin told a state television reporter.
"That would mean that NATO countries, the USA, European countries are at war with Russia," he added.
"If that is the case, then, taking into account the changing nature of the conflict, we will make appropriate decisions based on the threats we will face," he said.
Enabling Kiev to strike deep into Russia "is a decision about whether NATO countries are directly involved in a military conflict or not."
Putin's comments came a day after US Secretary of State Anthony Blinken gave his strongest hint yet that the White House was preparing to lift its restrictions on Ukraine using long-range Western-supplied weapons against key military targets inside Russia.
Speaking in Kiev alongside British Foreign Secretary David Lammy, Blinken said the US had been prepared "from day one" to adjust its policy as the situation on the battlefield in Ukraine changed.
"We will continue to do it", he emphasized.
Blinken said he and Lamy would report to their "bosses" -- Joseph Biden and Keith Starmer -- after their talks Wednesday with Ukrainian President Volodymyr Zelensky.
Lami suggested that Iran's shipment of ballistic missiles to Moscow - revealed this week - had changed strategic thinking in London and Washington.
It was a "significant and dangerous escalation," he said.
He added: "The escalator here is Putin. Putin escalated with the delivery of missiles from Iran. We see a new axis of Russia, Iran and North Korea".
Lami appealed to China not to "interfere" with, as he said, "a group of outlaws".
British government sources told the Guardian that a decision had already been made to allow Ukraine to use Storm Shadow cruise missiles against targets inside Russia, although it is not expected to be announced publicly on Friday when Starmer meets Biden in Washington.
The two leaders plan to discuss the war in Ukraine and how it might end as part of a broad foreign policy discussion, though they will avoid an intense focus on any one clue.
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