The UK is to station troops in the Baltic in order to counter "Russian aggression".

The "company-sized" deployment of UK armed forces will be sent to the Baltic states and Poland for the long-term in addition to the Baltic Air Policing detachment.

RAF Typhoon fighters have already been deployed in eastern Europe for some time and have been called into action in recent months as Russian jets have entered European airspace.

Russia responded to the announcement by saying such a move would be regrettable and would amount to Britain using an alleged Russian threat as camouflage to press ahead with NATO expansion.

It said that any move would be met with "parity".

British Defence Secretary Michael Fallon said the British troops would be part of a new NATO training, evaluation and capacity-building mission in Poland and the Baltic states of Latvia, Lithuania and Estonia.

There will also be an "uplift" in the number of personnel based in Ukraine to train local forces, the Ministry of Defence announced.

Mr Fallon is in Brussels to meet with other NATO defence ministers to discuss what to do about Russia's intervention in Syria. 

As he arrived for the meeting, Mr Fallon said the UK troop deployment was intended to reassure former Soviet bloc members of the alliance.

He said: "This is further reassurance for our allies on the eastern flank of NATO - for the Baltic states and for Poland.

"That is part of our more persistent presence on the eastern side of NATO to respond to any further Russian provocation and aggression."

At an afternoon news conference, NATO Secretary-General Jens Stoltenberg said alliance defence ministers had approved plans to establish two new headquarters in Hungary and Slovakia.

It had also agreed to double the size of its response force to as many as 40,000, twice the current size. 

The British deployment and NATO plans are the latest in a series of moves to strengthen the alliance's eastern borders following a series of developments involving Russia.

In 2014, Ukraine accused its neighbour of sending ground forces to help rebels fighting for partition in two of its eastern provinces. 

In June this year, RAF Typhoons were scrambled from Amari air base in Estonia to intercept and shadow two Russian military aircraft over the Baltic Sea.

It also comes as Russia has launched a series of cruise missile strikes on rebel targets in Syria from warships in the Caspian Sea.