Nato has announced plans to massively increase the number of its forces at high readiness to over 300,000 troops.
The bloc’s rapid reaction force currently has 40,000 troops at its disposal, with many of those based along the alliance’s eastern flank.
Secretary-General Jens Stoltenberg said the increase followed a direct threat from Russia to European security.
He earlier said that “the new military blueprint” would “drastically upgrade” the bloc’s eastern defences.
Mr Stoltenberg said several Nato battlegroups in eastern Europe would be bolstered to “brigade level” – tactical units of several thousand troops – which the bloc’s civilian leader said was intended to send a clear message of deterrence to Russia.
“I’m confident that Moscow, President Putin, understands our collective security guarantees, understands the consequence of attacking a Nato-allied country,” Mr Stoltenberg told reporters at a news conference in Brussels.