Britain has agreed to use its high-readiness Air Assault Brigade to further bolster Nato’s eastern flank, it emerged on Saturday night.

The new plans will see paratroopers become “fully integrated” into Estonia’s National Defence Plan.

It follows a pledge by the 31-member alliance to ramp up defence of its Eastern borders in readiness to counter any threats from Russia.

The UK already commits 1,000 troops to the Baltic state as part of Nato’’s Enhanced Forward Presence battlegroup.

EFPs were created in Estonia, Latvia, Poland and Romania after Russian forces invaded Donbas and illegally seized Crimea in 2014.

Britain has also deployed Apache helicopters to Estonia where it is supported by Danish, French and Icelandic troops who have deployed tanks, heavy artillery and advanced electronic warfare systems.

Now, this will be boosted by 16 Air assault Brigade, which acts as the UK’s Global Response Force – in a move designed to recognise the severity of the Russian threat.

As part of its new duties, the brigade will also spearhead a major reinforcement exercise next year.

Spring Storm will see as many as 4,000 paratroopers descend into the north of the country and stay on the ground for up to three months.

The idea, senior sources say, is to create a seamless way of delivering the troop boost at very short notice.

Estonia has been at the forefront of border tensions for almost 10 years.

More than 310,000 of Estonia’s 1.3 million population identify as ethnic Russians, with many sourcing their news from television based in Moscow.

Estonia’s PM Kaja Kallas has responded to any potential internal threat by systematically removing Soviet imagery, such as monuments commemorating the Second World War.

Last year there were angry scenes when the Estonian government removed a Soviet-era T-34 tank from its pedestal in the eastern city of Narva, where 95.7 percent of the population are native Russian speakers and 87.7 percent are ethnic Russians.

Russia forces have mounted exercises close to the Estonian border, eavesdropped on military communications and deployed highly skilled female agents working for Russia’s secret service, the FSB, who have tried to solicit information from off-duty soldiers.

Nato’s focus on reinforcement follows a decision by Latvia to reintroduce national service after it was abolished 15 years ago. Next week the government’s audit of the Integrated Defence Review will be announced with the 16 Air Assault Brigade being given centre stage in its role as the Global Response Force.

In other news, former Russian PM Dmitry Medvedev on Saturday night claimed that Boris Johnson should be “admitted to a psychiatric hospital” for wanting Ukraine to become an immediate Nato member.

Ukrainian president Volodymyr Zelensky had hoped last week’s Nato summit in Vilnius, Lithuania, would deliver a guarantee that Ukraine would join the alliance as soon as the war with Russia was concluded.

Instead, complained Boris Johnson, ”all the Ukrainians got this week was an invitation to join Nato when allies are agreed and when conditions are met.

“No wonder President Zelensky found it hard, at first, to conceal his frustration.”

In a tirade which, experts say, reveals the depth of Russian concern, Medvedev -now deputy head of Vladimir Putin’s security council – said: “Former Britain’s PM [Boris] Johnson suggested admitting Ukraine to NATO without conditions. He, a retired idiot, should be admitted to a psychiatric clinic without conditions”