If Putin's ambitions in Ukraine were to halt the growth of Nato, the reaction in Europe has been the opposite as ITV News' Rageh Omaar reports.
Boris Johnson has promised to give Sweden and Finland whatever kind of assistance they request if they come under attack, including military support.
His comments come following the signing of an historic security assurance agreement with the two nations, pledging to "bolster military ties" in the face of Russia's invasion of Ukraine.
Explaining the deals with Finland and Sweden, Mr Johnson said: "In the event of a disaster or an attack we will come to the other's assistance, upon request, and it will be up to the other party to say what kind of assistance they want."
The offer of support to the Nordic region, includes deployment of Royal Air Force, British Army and Royal Navy personnel and assets.
As the security and future of European nations changes as the war in Ukraine changes, ITV News International Affairs Editor Rageh Omaar explains what the deals with Finland and Sweden mean.
But, asked whether the the UK's nuclear deterrent was included in the assurance, Mr Johnson ITV News that it's "very important that we don't discuss the use or deployment of our nuclear weapons, or indeed the conditions on which me might deploy them".
Under the agreements both countries would be expected to provide the UK with support, should it be requested. Both nations are also considering whether to join Nato.
It suggests there's been a shift in position from two countries which have previously opted out of military alliances and have historically remained neutral in wartime.
But for Nordic countries, their proximity to Russia is concerning, especially for Finland, which shares a lengthy land border with Russia and is only about 250 miles from St Petersburg.
Mr Johnson said Russia invasion of Ukraine shows "any country that is independent, democratic, within range of Vladimir Putin, is potentially a target".
ITV News Political Correspondent explains how Russia may react to the announcement.
He then told a press conference in Finland that the deals signed will see each other "always come to one another's aid", whether or not the countries join Nato.
"This is not a short-term stop gap as you consider Nato membership, but an enduring assurance between two nations, an assurance that brings us ever closer as we face the challenges of today, the threats of tomorrow, side by side."
Asked during a press conference alongside Finnish president Sauli Niinisto if there would be "British boots on the ground" on Finnish territory during a "possible conflict with Russia", he said: "I think the solemn declaration is itself clear.
"And what it says is that in the event of a disaster, or in the event of an attack on either of us, then yes, we will come to each other's assistance, including with military assistance.
Boris Johnson - 'The UK would come to the assistance of Sweden with whatever Sweden requested'
Swedish prime minister Magdalena Andersson said her country would be safer as a result of the mutual assistance agreement with the UK.
"Are we safer with this declaration? Yes we are. Of course this means something. This is important whatever policy choice we make in Sweden," she said.
Despite early hopes that negotiations with Russia could find a resolution to the conflict, Mr Johnson suggested that outcome was currently not possible.
"How can the Ukrainians negotiate with the crocodile when its got their limbs in its jaws - which is what's happening," he said, "how can you negotiate with a burglar who's in the middle of carrying out violent armed robbery in your own house?"
Mr Johnson said there was a "sad irony" that the agreement was being signed just days after Europe celebrated victory over Nazi Germany on VE Day, but said it was necessary given the "grim circumstances" surrounding Putin's invasion.
"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."
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".
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