The US has unveiled fresh details of its plan to create a Russia-deterrent force in eastern Europe, prompting Russia to warn of an “asymmetric response” and of a potential “crisis”.

The Pentagon said in a statement on Wednesday (30 March) that from February 2017 a brigade-sized force will begin rotating its troops in and out of Bulgaria, Estonia, Latvia, Lithuania, Hungary, Poland and Romania.

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Breedlove (c) with German defence minister Ursula von der Leyen (Photo: 1GNC Munster)

The troops - up to 4,500 soldiers - would switch from location to location every nine months and conduct regular exercises with host nation forces.

They’ll bring with them modern tanks and armoured personnel carriers which will be stored in warehouses in the region, gradually replacing older equipment which will be moved to depots in Belgium, Germany, and the Netherlands.

The new materiel will include 250 tanks, armoured personnel carriers and self-propelled artillery pieces as well as 1,700 other vehicles and trucks, the US daily the Wall Street Journal said, citing Robert Work, the US deputy defence chief.

The idea of creating a Russia-deterrent force was first outlined at a Nato summit in Wales in 2014 after Russia invaded Ukraine. It comes amid concerns that Moscow’s next move could be to destabilise one of Nato’s eastern allies.

The US earlier this year also announced that it would quadruple military spending on its European forces to $3.4 billion, with Wednesday’s announcement adding detail to the plans.

General Philip M. Breedlove, the commander of US forces in Europe, said: “This is a big step in enhancing the army's rotational presence and increasing their combat equipment in Europe.

“This army implementation plan continues to demonstrate our strong and balanced approach to reassuring our Nato allies and partners in the wake of an aggressive Russia in eastern Europe and elsewhere.”

The US army statement added: “The [new] equipment will enable rapid deployment of ground forces and additional combat power in response to contingencies throughout the region.”

Work also told The Wall Street Journal: “If push came to shove, they [the rotational force] would be able to come together as a cohesive unit that has trained together, with all their organic equipment, and fight. That’s a lot better than what we have right now.”

Reacting to the news, Russia’s envoy to Nato, Alexander Grushko, told the Russia 24 TV channel on Wednesday: “Certainly, we’ll respond totally asymmetrically.

“We are not passive observers, we consistently take all the military measures we consider necessary in order to counterbalance this reinforced presence that is not justified by anything.”

An “assymetric” response refers to military, diplomatic, or economic countermeasures which are not the direct equivalent of the US military build-up.

Grushko added that if Nato yielded to Georgian and Ukrainian overtures to join the military alliance: “This would explode the situation and put Europe on the brink of a crisis, whose size and scale can’t be imagined today.”

Russia this week also opted to send a senior diplomat instead of its president or PM to a nuclear non-proliferation summit in Washington.

“As we’ve said all along, we would welcome a stronger Russian role with respect to fighting Daesh [Islamic State], so it’s not just about nuclear security this week,” US state department spokesman John Kirby said.

“We think … it’s important for Russia to be a participant in these kinds of talks.”

The US pivot back to Europe comes after US president Barack Obama had said he would draw down his forces in the region in favour of giving more attention to security concerns in the Pacific area.

It also comes amid differences of opinion between Moscow and Western capitals on the meaning of a 1997 Nato-Russia pact on limiting new troop deployments.

The US step is unlikely to be welcomed in some EU and Nato capitals.

“For all the faults of Russia, its show of muscles, its power-policy, but also for that same reason we should be careful about surrounding Russia too much with Nato,” admiral Luigi Binelli Mantelli, who was until recently Italy’s chief of defence, told EUobserver in a recent interview.

“They have a different approach. We’re more confident. But they’re not so confident in the [Nato-Russia] relationship.”