NATO Secretary-General Jens Stoltenberg acknowledged on Wednesday that the 30-member alliance could have done more to help Ukraine in the lead-up to the Russian invasion three weeks ago.

Following an extraordinary meeting with NATO defense ministers, Stoltenberg told reporters the alliance is looking to "reset" its deterrence and defense systems in the face of Russian aggression – including how it aids non-NATO nations.

Jens Stoltenberg

NATO Secretary General Jens Stoltenberg speaks during a media conference after a meeting of the NATO-Ukraine Commission at NATO headquarters in Brussels. (AP Photo/Olivier Matthys)

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"I think we need to realize that we are faced with a top new security reality, which of course affects the people of Ukraine – it's devastating for them," the NATO chief said. "But it's also putting more pressure on those countries in our neighborhood who are not members of NATO."

Stoltenberg said nations like Georgia, which was formally a part of the Soviet Union and struggled under a Russian invasion in 2008, face an increased threat from Moscow aggression. 

"One of the lessons we have to learn from what is going on in Ukraine today is that we need to support these countries, which are at risk now," Stoltenberg told reporters. "If anything, I think we now see the value of the support that has been provided to Ukraine before the invasion, but also the importance of that we could have done even more for Ukraine."

The secretary-general said officials in each NATO nation have been tasked with developing military defenses across every arena, including land, air, sea, cyber and space, to counter the threat that Russia poses. 

Defense systems, coordinated military trainings and pre-positioned equipment in the Eastern European flank will be advanced in an effort to ensure Moscow understands NATO’s force posture.

There are hundreds of thousands of troops on heightened alert in Europe, including 100,000 U.S. troops, Stoltenberg said but added that every NATO nation needed to invest at least 2% of its GDP in defense. 

U.S. Army troops walk on the tarmac at Rzeszow-Jasionka Airport, southeastern Poland, on Feb, 16, 2022.

U.S. Army troops walk on the tarmac at Rzeszow-Jasionka Airport, southeastern Poland, on Feb, 16, 2022. (WOJTEK RADWANSKI/AFP via Getty Images)

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Stoltenberg said NATO’s security readiness in Europe has not been updated since 1997 when it signed the NATO Russia Founding Act. 

"We are in a total different security environment. At that stage we actually foresaw Russia as a strategic partner," he said. "Since then Russia has invaded Georgia, illegally annexed Crimea and now also invaded Ukraine."

Despite NATO’s renewed promise to aid Ukraine with military supplies, financial help and humanitarian aid, the alliance once again said it will not block Russian air capabilities. 

Just moments after Ukrainian President Volodymyr Zelenskyy made an impassioned plea to the U.S. Congress and President Biden to institute a no-fly zone, Stoltenberg said NATO is united in opposing the move.

Ukrainian emergency employees and volunteers carry an injured pregnant woman from a maternity hospital damaged by shelling in Mariupol, Ukraine, Wednesday, March 9, 2022.  (AP Photo/Evgeniy Maloletka)

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"We have a responsibility to ensure that this conflict, this war, doesn't escalate beyond Ukraine," Zelenskyy said. "We see death, we see destruction, we see human suffering in Ukraine. But this can become even worse."

NATO leaders continue to fear that if the U.S. or any allied nations blocked Russian air abilities, the war would spill beyond Ukraine into Europe and could spark a "full-fledged war between NATO and Russia."