The move comes as the two Nordic countries mull NATO membership amid warnings from Russia
The UK has agreed "mutual security assurances" with Sweden and Finland, British Prime Minister Boris Johnson revealed on Wednesday, a few days before Stockholm and Helsinki are due to announce their decision on pursuing NATO membership.
Johnson is visiting both countries today to sign "historic" declarations, the prime minister's office said in a statement.
According to Downing Street, the new pacts involve "intensifying intelligence sharing, accelerating joint military training, exercising and deployments, and bolstering security across all three countries and northern Europe."
The UK also intends "to support the two nations armed forces should either face crisis or come under attack," the office said. This reassurance comes as both Finland and Sweden previously expressed concern of possible retaliation from Russia should they apply for NATO membership.
Speaking during a press conference in Sweden, Johnson claimed that the Russian military attack on Ukraine - which he described as "Putin's bloodthirsty campaign against a sovereign nation" - put an end to the hope that peace in Europe will endure.
"The war in Ukraine is forcing us all to make difficult decisions. But sovereign nations must be free to make those decisions without fear or influence or threat of retaliation," the UK prime minister said, adding that he is "very pleased" to sign the declaration.
The news of the security pacts comes amid reports that several other countries will soon be joining the UK in providing security assistance to Sweden and Finland. According to the Norwegian newspaper Verdens Gang, Nordic NATO countries Norway, Denmark and Iceland are working with their neighbors on a joint political declaration which could provide Stockholm and Helsinki with additional assurances in the coming months.
On May 6, White House spokeswoman Jen Psaki reassured Sweden and Finland that the United States will be able to find ways "to address any concerns either country may have about the period of time between a NATO membership application and the formal accession to the alliance."
Amid Moscow's ongoing military offensive in Ukraine, both Sweden and Finland, which has a lengthy border with Russia, have seen a dramatic change in public opinion, with the majority of the population now supporting joining the US-led bloc, according to polls. This prompted authorities in both countries to reconsider their long-standing non-alignment policy.
Sweden's ruling party will reveal its stance on NATO membership on May 15, three days after a similar move is expected to be taken by Finland. While the Swedish Social Democrats, according to their Secretary-General Tobias Baudin, have not yet come to a final decision, the Finnish government has reportedly formulated their position and it is "that Finland is applying for membership." The parliament is reportedly expected to give its approval as well.
In early April, the head of the military alliance, Jens Stoltenberg, said NATO "will warmly welcome" Finland and Sweden if they apply to join, and is prepared to make a decision on membership "quite quickly."
Russia considers the further expansion of NATO to be a direct threat to its own national security, and "for the whole architecture of security." Kremlin spokesperson Dmitry Peskov warned in April that Moscow would "take additional measures" to make its defenses on the Western flank "more sophisticated" if Finland and Sweden join the bloc.