The United Kingdom on Wednesday shored up its defense alliances with Sweden and Finland in a move to strengthen European security in light of Russia’s aggression on the continent’s eastern flank. 

"Today we made history by signing a joint declaration of solidarity to strengthen our security and defense ties and bring our nations even closer together," UK Prime Minister Boris Johnson said in a tweet after meeting with his Swedish counterpart. "We are literally and metaphorically in the same boat."

CRUCIAL NATO DECISIONS EXPECTED IN FINLAND, SWEDEN THIS WEEK

The agreements will not only provide Sweden and Finland with assurances that the U.K. will come to its aid should it be attacked by Russia, but it sends a warning signal to Russian President Vladimir Putin.

The traditionally neutral nations have looked to join the 30-member NATO alliance following Russia’s invasion of Ukraine in late February.

In the lead-up to the incursion, Russia repeatedly demanded that NATO block Ukraine from joining the military alliance and deny it access to the Article 5 statute – which says that an attack on one nation will trigger a response from the entire alliance.

Ukraine has not become a NATO member, but the military alliance has backed Kyiv throughout the war by providing billions of dollars worth of defensive and humanitarian aid.

British Prime Minister Boris Johnson, left, and Finland's President Sauli Niinisto, arrive at the Presidential Palace for talks, in Helsinki, Finland, Wednesday, May 11, 2022. 

British Prime Minister Boris Johnson, left, and Finland's President Sauli Niinisto, arrive at the Presidential Palace for talks, in Helsinki, Finland, Wednesday, May 11, 2022.  (AP Photo/Frank Augstein, Pool)

Putin has long considered the NATO alliance among its greatest threats despite relatively calm geopolitical relations prior to its invasion of Ukraine. 

Western officials have repeatedly claimed that Putin’s aim was to break up NATO and regain former Soviet territory by launching a major military offensive and causing the greatest humanitarian crisis since World War II in Europe.

SWEDEN SAYS IT RECEIVED US SECURITY ASSURANCES IF IT SUBMITS NATO APPLICATION

But NATO has shown a united front and now other European nations are looking to the alliance to shore up their own security guarantees. 

Last month Moscow threatened that if Sweden and Finland joined the military alliance then it would position nuclear weapons and hypersonic missiles along its western border. 

"What we are saying, emphatically, is that in the event of a disaster or the event of an attack upon Sweden, then the UK would come to the assistance of Sweden with whatever Sweden requested," Johnson said after meeting Swedish Prime Minister Magdalena Andersson, first reported Reuters. 

British Prime Minister Boris Johnson, left, and Sweden's Prime Minister Magdalena Andersson arrive for a joint press conference in Harpsund, the country retreat of Swedish prime ministers, Wednesday, May 11, 2022. 

British Prime Minister Boris Johnson, left, and Sweden's Prime Minister Magdalena Andersson arrive for a joint press conference in Harpsund, the country retreat of Swedish prime ministers, Wednesday, May 11, 2022.  (AP Photo/Frank Augstein, Pool)

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Wednesday’s agreements mean Sweden and Finland would be guaranteed security defenses from the U.K. while their applications for NATO membership are completed. 

The U.S. and Germany have already agreed to back the northern European nations against Russian aggression.