NATO Secretary General Jens Stoltenberg has warned that a Russian attack on the supply lines of allied countries supporting Ukraine with weapons and ammunition would be a dangerous escalation of the war raging in Eastern Europe, CBC News reported.

"The allies are helping Ukraine uphold their right for self defence, which is enshrined in the UN charter. Russia is the aggressor and Ukraine is defending itself. If there is any attack against any NATO country, NATO territory, that will trigger Article 5," Stoltenberg said in an interview with CBC News.

Article 5 is a self-defence provision in NATO's founding treaty, which states that an attack on one NATO member is an attack on all 30 member countries.

"I'm absolutely convinced President Putin knows this and we are removing any room for miscalculation, misunderstanding about our commitment to defend every inch of NATO territory," Stoltenberg said.

The Secretary General said there is a clear distinction between supply lines inside Ukraine and those operating outside of it.

"There is a war going on in Ukraine and, of course, supply lines inside Ukraine can be attacked," he said.

The Secretary General emphasized that an attack on NATO territory, on NATO troops, NATO capabilities would be an attack on NATO.

Stoltenberg said NATO's message to Russia is that "they have to end the war, that we will continue to support Ukraine and that we continue to impose unprecedented sanctions."