"Every nation that is attacked has the right to defend itself. And that right doesn’t stop at the border of your own nation,” stated Admiral Rob Bauer, the head of NATO's military committee.

This statement from the NATO commander comes a day after US President Joe Biden signalled his openness for Kyiv using Western long-range missiles inside Russia.

However, Admiral Bauer added that while a nation has a right to defend itself, the countries providing it with weapons must place limitations on their use.

"In military terms, you do (those attacks) because you want to weaken the enemy that attacks you in order to not only fight the arrows that come your way but also attack the archer. So, militarily, there is a good reason to do that; to weaken the enemy, to weaken its logistics lines, fuel, ammunition that comes to the front," stated Bauer.

As the war escalates, Ukrainian President Volodymyr Zelenskyy has been asking allies to allow the use of Western missiles to strike targets inside Russia.

However, Russian President Vladimir Putin has stated that if NATO allows Ukraine to carry out such attacks and the use of long-range missiles, it would mean NATO is "at war" with Moscow.

"This will mean that NATO countries – the United States and European countries – are at war with Russia. And if this is the case, then, bearing in mind the change in the essence of the conflict, we will make appropriate decisions in response to the threats that will be posed to us,” Putin told reporters on Thursday.

A similar message was echoed by the Russian ambassador to the UN during a Security Council meeting.

Vassily Nebenzia stated that the Western countries allow Ukraine to conduct long-range missle strike in Russia, it would mean they are at "War with Russia".

"The facts are that NATO will be a direct party to hostilities against a nuclear power, I think you shouldn’t forget about this and think about the consequences,” said the Russian envoy.