NATO Secretary-General Jens Stoltenberg  has warned Russia that any act of aggression against a member of the alliance would not be tolerated.

Stoltenberg said defense plans had already been activated to shield the alliance in light of Russia's invasion of Ukraine, which is set to enter its third week.

What exactly did the NATO boss say?

"Moscow should not be in no doubt, NATO will not tolerate any attack on allied sovereignty or territorial integrity."

"We face a new reality for our security. So we must reset our collective defense and deterrence for the longer term," Stoltenberg said.

The NATO chief said military commanders had been tasked with bolstering defense across land, air and sea on the the alliance's eastern flanks.

He said attention was also being paid to cyber and space threats.

NATO defense ministers on Wednesday tasked military commanders to come up with plans to bolster the alliance's eastern flanks.

"On land, our new posture should include substantially more forces in the eastern part of the alliance, at higher readiness, with more pre-positioned equipment and supplies," Stoltenberg told reporters.

The NATO chief said that allies needed to train together more often and "in greater numbers" and stressed the need for members to spend a minimum of 2% of GDP on defense. Germany and Denmark's investments to that end were welcomed.

No-fly zone ruled out

The extraordinary meeting of NATO defense ministers was held in Brussels focused on Russia's invasion of Ukraine and the impact on regional security in eastern Europe.

Stoltenberg said defense chiefs had agreed to "continue to provide significant support to Ukraine, including with military supplies, financial help and humanitarian aid."

However, he ruled out any role for the military organization in setting up and policing a no-fly zone to protect against
Russian airstrikes.

"NATO should not deploy forces on the ground or in the air space over Ukraine because we have a responsibility to
ensure that this conflict, this war, doesn't escalate beyond Ukraine," he said.

Stoltenberg called on Russian President Vladimir Putin to end hostilities.

"President Putin must stop this war immediately. Withdraw his forces now and engage in diplomacy in good faith."

The special meeting of 30 NATO defense ministers included United States Secretary of Defense Lloyd Austin.

Troops on 'heightened alert'

Earlier on Wednesday Stoltenberg spoke of the impact the war was having on regional security.

"This is devastating for the Ukrainian people and it will also change our security environment. It will have long-lasting consequences for our security, for all NATO allies," Stoltenberg said.

The NATO chief said the alliance was reinforcing its collective defense, adding that "hundreds of thousands of troops were on heightened alert."

According to Stoltenberg, 100,000 US troops are in Europe, with 40,000 under direct NATO command.

Stoltenberg said that both the immediate and long-term consequences of Russia's actions would be spoken about, with emphasis on strengthening the defense of all NATO members.

The secretary-general stressed that NATO had a responsibility to ensure the "crisis" didn't escalate beyond the borders of Ukraine, which explains bolstered troop numbers along the eastern flank of the alliance.

Next week, an extraordinary summit of NATO leaders is due to be held.

Ukraine's ties to NATO and the EU

Ukraine has been looking to become a European Union member state and a NATO member for years. But over the weekend, EU leaders made it clear that there could be no shortcut to EU membership, following a two-day informal summit at the Palace of Versailles in France.

The country's hopes of becoming part of the NATO security alliance also don't appear to be any closer to materializing, something that Ukrainian President Volodymyr Zelenskyy appeared to concede on Tuesday.

"Ukraine is not a member of NATO, we understand that. We are decent people. We've heard for years that the doors were open, but we also heard that we could not join. That's the truth and it must be recognized. I'm glad that our people are beginning to understand this, and rely on themselves and our partners who are helping us,"  Zelenskyy said.

Russia views Ukraine's NATO aspirations as a threat to its security and has accused the alliance of encroaching eastward.

kb/sms (dpa, Reuters)