Speaking after chairing an emergency meeting of NATO envoys, Stoltenberg said the 30-nation security alliance will continue to beef up its defenses on its eastern flank near Ukraine and Russia. He said U.S. President Joe Biden and his NATO counterparts will hold an online summit on Friday.

“Russia has attacked Ukraine. This is a brutal act of war. Our thoughts are with the brave people of Ukraine,” Stoltenberg told reporters. “Peace in our continent has been shattered. We now have war in Europe, on a scale and of a type we thought belong to history.”

“NATO is the strongest alliance in history, and make no mistake we will defend every ally against any attack on every inch of NATO territory,” he said at the organization’s Brussels headquarters. “An attack on one ally will trigger a response from the whole alliance.”