BRUSSELS, Feb. 22 (Xinhua) -- The chief of the North Atlantic Treaty Organization (NATO) has urged Russia to "choose the path of diplomacy" in the conflict with Ukraine.

"This is the most dangerous moment in European security for a generation," NATO Secretary General Jens Stoltenberg said at the conclusion of an extraordinary meeting of the NATO-Ukraine Commission here on Tuesday.

"Europe and North America continue to stand strong together in NATO, committed to defend and protect each other," he said.

He said NATO put its Response Force on higher readiness several weeks ago and has 100 jets on high alert and 120 ships at sea.

NATO Secretary General Jens Stoltenberg gives a press briefing following a extraordinary meeting of the NATO-Ukraine commission about the situation between Ukraine and Russia, at NATO headquarters in Brussels on February 22, 2022. (Photo: AFP)

He welcomed the economic sanctions announced by many NATO allies and the decision by the German government that it cannot certify the Nord Stream 2 pipeline.

Stoltenberg also said that Russian forces continue to prepare for a potential attack on Ukraine after Moscow recognized two separatist regions as independent.

Russian President Vladimir Putin on Monday signed two decrees recognizing the "Lugansk People's Republic (LPR)" and the "Donetsk People's Republic (DPR)" as independent and sovereign states.

The European security crisis was caused by NATO's eastward expansion, which has led to the loss of mutual trust, Putin said on Monday.

He said it was just for NATO to accept Ukraine as a member state and then build facilities on its territory, which would dramatically raise the level of military threats to Russia.