President Vladimir Putin delivered a clear message to the West about the consequences it will face if it allows Ukraine to hit Russian territory with Western long-range missiles, the Kremlin has said.
Mr Putin's comments come as British Prime Minister Keir Starmer and US President Joe Biden will discuss whether to let Ukraine use long-range missiles against Russia.
British media reported that Mr Biden, who is wary of provoking a nuclear conflict, was ready to let Ukraine deploy British and French missiles using US technology but not US-made missiles themselves.
Mr Putin said that the West would be directly fighting with Russia if it allowed Ukraine to strike Russian territory with Western-made long-range missiles, a move he said would alter the nature and scope of the conflict.
"The statement made by President Putin yesterday is very important. It is extremely clear, unambiguous and does not allow for double readings. We have no doubt that this statement reached those it was intended for," Kremlin spokesman Dmitry Peskov said.
President Volodymyr Zelensky has been pleading with Ukraine's allies for months to let Ukraine fire Western missiles including long-range US ATACMS and British Storm Shadows deep into Russian territory to limit Moscow's ability to launch attacks.
President Putin said that such a move would drag the countries supplying Ukraine with long-range missiles directly into the war.
He said satellite targeting data and programming of the missiles' flight paths would have to be provided by NATO military personnel, as Ukraine did not have the capabilities itself.
"If this decision is taken, it will mean nothing less than the direct involvement of NATO countries, the United States and European countries in the war in Ukraine," he said, and Russia would be forced to take "appropriate decisions".
