Western countries approving Ukraine’s use of long-range weapons to hit targets in Russia would mean NATO will be “at war” with Moscow, President Vladimir Putin said Thursday.

“This would significantly change the very nature of the conflict… It would mean that NATO countries, the U.S. and European countries are at war with Russia,” Putin told a state television reporter.

Putin spoke as US and UK top diplomats discussed easing rules on firing Western weapons into Russia, which Kyiv has been pressing for, more than two and a half years into Moscow’s offensive.

“If that’s the case, then taking into account the change of nature of the conflict, we will make the appropriate decisions based on the threats we will face.”

Clearing Kyiv to strike deep into Russia “is a decision on whether NATO countries are directly involved in the military conflict or not,” Putin said.

Putin’s comments came as Kyiv pressed the West to provide more powerful weapons with fewer restrictions, as Russia continues its advance into eastern Ukraine.

UK Prime Minister Keir Starmer who commented on Putin’s remarks en route to Washington has told Putin that he started the war in Ukraine and could end it at any time.