NATO Secretary-General Jens Stoltenberg spoke at a special briefing in Brussels in connection with Russia's attack on Ukraine, but did not give a direct answer whether the alliance would provide military assistance, European Pravda reported.

"NATO stands in solidarity with Ukraine and NATO allies are imposing severe costs on Russia for the reckless invasion of Ukraine. NATO allies, in close coordination with the European Union and other partners all over the world, are now imposing severe economic sanctions on Russia," Stoltenberg said.

The secretary-general was asked directly whether NATO planned to send troops into Ukraine, to which he replied "NATO’s core task is to protect and defend all Allies."

When asked about the same thing a second time, he said NATO had tried to thwart the conflict by warning of Moscow's plans and threatening sanctions. "Russia has shut the door to a diplomatic solution. We regret that," he said.

Stoltenberg later added that NATO has no troops on Ukrainian territory and has no plans to deploy.

Stoltenberg added that the North Atlantic Alliance was convening an urgent summit by video link to decide on a way forward.

The alliance has also activated a pre-designed defence plan to facilitate the movement of troops, including a rapid reaction force that also includes more than 100 aircraft and 120 ships.