(Update 15:10pm ET): NATO Chief Stoltenberg announced oN Friday that elements of the 40,000 troop-strong NATO Response Force (NRF) would be activated for the first time.

As Axios notes:

Stoltenberg has called Russia's invasion of Ukraine "the most serious security crisis we have faced in Europe for decades." The NRF will deploy "on land, at sea, and in the air" in eastern Europe for the purposes of collective defense.

Details: The secretary general said that the size of the NRF has tripled since 2014, but that not all forces would be deployed. He also said that NATO countries would be providing additional weapons and air-defense systems to Ukraine at the request of its government.

What he's saying: "We are deploying [the NRF] to ... prevent any miscalculations, any misunderstandings that we are not ready to protect and defend all our allies," Stoltenberg said. "This is something that all allies have agreed to do."

• He added that eastern-flank allies "are extremely concerned. They are close to the fighting in Ukraine, and they also border Russia, and they've seen not only the military buildup and the ongoing war in Ukraine, but also seen the very threatening rhetoric because this goes far beyond Ukraine."
• "Russia's attack on Ukraine is more than an attack on Ukraine. It's a devastating horrendous attack on innocent people in Ukraine, but it's also an attack on the whole European security order. And that's the reason why we take it so extremely seriously," Stoltenberg said.