NATO: Risk of conflict in Ukraine crisis is real

Stoltenberg told reporters NATO allies called on Russia "to de-escalate and any further aggression will come with a high cost for Moscow," adding NATO was a "defensive alliance which does not threaten Russia or any other country."

Germany is ready to discuss halting the Nord Stream 2 pipeline should Russia attack Ukraine, Scholz said, responding to increasing domestic and international pressure amid the Russian military build-up on Ukraine's borders.

"It is clear that there will be a high price to pay and that everything will have to be discussed should there be a military intervention in Ukraine," Scholz told reporters, responding to a question on Nord Stream 2.

Stoltenberg said he had invited NATO allies and Russia to a series of meetings at the NATO-Russia Council to discuss ways to improve the security situation, after a first round of talks was held last week in Brussels.