reports.
The troops will serve as a "follow-on force" to Nato's response force which can be deployed to a warzone in days.
The soldiers will come from the alliance's 28 member states including Britain.
Jens Stoltenberg, the former prime minister of Norway and the alliance's secretary general, told The Times: "We have seen Russia being much more active in many different ways.
"We have seen a more assertive Russia implementing a substantial military build-up over many years; tripling defence spending since 2000 in real terms; developing new military capabilities; exercising their forces and using military force against neighbours.
"We have also seen Russian using propaganda in Europe among Nato allies and that is exactly the reason why Nato is responding.
"We are responding with the biggest reinforcement of our collective defence since the end of the Cold War."
Vladmir Putin and Russia recently unveiled their new and deadly "Satan 2" nuclear warhead Credit: AP:Associated Press The measures were drawn up after Russia annexed Crimea in 2014 and engaged in a conflict with Ukraine.
They include the deployment of 4,000 Nato troops to Latvia, Lithuania, Poland, and Estonia from 2017.
A quarter of those would be from the UK military.
The alliance already has a response team of 5,000 ground troops which are supported by air, sea and special forces, and can be deployed within five days.
Mr Stoltenberg has said Nato want to increase the readiness of many of its 3million soldiers, airmen, Marines, and sailors.
He added: "We are... addressing what we call the follow-on forces".
Mr Stoltenberg continued: "There are a large number of people in the armed forces of Nato allies.
"We are looking into how more of them can be ready on a shorter notice".
"We have seen a more assertive Russia implementing a substantial military build-up over many years": NATO Secretary-General Jens Stoltenberg explains part of the reason for the alliance's latest action Credit: Reuters Most member states reduced their defence budgets and decreased the size of their military after the collapse of the Soviet Union.
However, Russia has continued to grow its military and holds exercises of more than 100,000 personnel each year.
Nato has responded to an increase in espionage, hybrid warfare and cyber attacks by Russia and other non-Nato states by creating an intelligence division.
Mr Stoltenberg has said it is important Russia and Nato keep communicating.
Russia's recent military posturing has prompted fears a new Cold War era is set to begin.
The country has also unveiled its "Satan 2" nuclear warhead which could "destroy and area the size of England and Wales twice over".
It is also rumoured the super-size nuke could wipe out an area the size of France.
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