Boris Johnson is in Sweden and Finland to sign historic security assurance declarations today as he sends a stark message to Vladimir Putin.

The PM is inking pledges to ‘bolster military ties’ and support both countries should they come under attack.

Mr Johnson arrived in Stockholm before travelling to Harpsund, the country residence of his Swedish counterpart, Magdalena Andersson, where he set out a UK commitment to come to the country’s aid in the event of a crisis.

Mr Johnson is set to visit to Finland later, where he is expected to formalise a similar agreement with the country’s President Sauli Niinisto during a whirlwind 24 hours.

An offer to increase deployments to the region, including with Royal Air Force, British Army and Royal Navy personnel and assets, will also be made.

Boris Johnson arrived in Stockholm before travelling to Harpsund, the country residence of his Swedish counterpart, Magdalena Andersson, where he set out a UK commitment to come to the country’s aid in the event of a crisis

The PM (pictured in Sweden) is inking pledges to ‘bolster military ties’ and support both countries should they come under attack

Both countries consider the prospect of Nato membership in the face of Putin’s ongoing military aggression

It comes as both countries consider the prospect of Nato membership in the face of Russian President Vladimir Putin’s ongoing military aggression.

But the Kremlin has warned that it is ‘watching very closely anything that can affect NATO configuration near our borders’.

Mr Johnson said: ‘We are steadfast and unequivocal in our support to both Sweden and Finland and the signing of these security declarations is a symbol of the everlasting assurance between our nations.

‘These are not a short-term stop-gap, but a long-term commitment to bolster military ties and global stability, and fortify Europe’s defences for generations to come.’

The declarations build on claims made earlier in the month that the UK would always aid Finland if it were attacked by Russia, regardless of whether the country was a member of Nato.

Defence Secretary Ben Wallace said it was ‘inconceivable’ that Britain would not help either Finland or Sweden if it were in crisis, even ‘without any big formal agreement’.

Mr Johnson held talks with Ms Andersson and Mr Niinisto in March as part of a meeting of the Joint Expeditionary Force nations, which includes Denmark, Estonia, Iceland, Latvia, Lithuania the Netherlands and Norway.

After the meeting, Downing Street said the two leaders agreed that ‘Putin’s invasion had dramatically changed the landscape of European security’.

Finland shares a lengthy land border with Russia and is only about 250 miles from St Petersburg.