NATO said on Monday it was putting forces on standby and reinforcing eastern Europe with more ships and fighter jets, and could also send additional troops to its south-east flank, in what Russia denounced as an escalation of tensions over Ukraine.
Welcoming a series of deployments announced by alliance members in recent days, Secretary General Jens Stoltenberg said NATO would take "all necessary measures."
The move was a further sign that the West is bracing for Russia to attack its neighbour after massing an estimated 100,000 troops in reach of the Ukrainian border.
"We will always respond to any deterioration of our security environment, including through strengthening our collective defence," Stoltenberg said in a statement.
He later told a news conference that the enhanced presence on NATO's eastern flank could include the deployment of additional NATO battlegroups.
"We are considering also to have battlegroups... in the southeast of the alliance," Stoltenberg said.
So far, NATO has about 4,000 troops in multinational battalions in Estonia, Lithuania, Latvia and Poland, backed by tanks, air defences and intelligence and surveillance units.
Russia denies planning an invasion. But, having engineered the crisis by surrounding Ukraine with forces from the north, east and south, Moscow is now citing the Western response as evidence to support its narrative that Russia is the target, not the instigator, of aggression.
U.S. officials said the Pentagon was finalising efforts to identify specific units that it could deploy to NATO's eastern flank.
One of the officials said up to 5,000 could be deployed, while a NATO diplomat said Washington was considering gradually transferring some troops stationed in western Europe to eastern Europe in the coming weeks. read more
U.S. President Joe Biden will hold a video call with European leaders later on Monday as part of the coordination with allies to respond to Russia's build-up on Ukraine's borders, the White House said.
