The Prime Minister welcomed Fumio Kishida to Number 10 on the Japanese leader’s first visit to London since taking office. They agreed a reciprocal access agreement that will lead to close military cooperation including joint exercises in the Indo-Pacific region.
Mr Johnson said allies in Europe and east Asia had to be unified in the face of “autocratic, coercive powers”.
He was understood to be referring to Russia, China and North Korea.
Mr Johnson said the world has observed the “strong stance” the Japanese government has taken “against the Russian aggression in Ukraine”.
He added: “We in the UK recognise that our security in Europe is indivisible from the security, our collective security, in the Asia-Pacific, in the Indo-Pacific region.
“And there is direct read across from the actions of autocratic, coercive powers in Europe, to what may happen in east Asia.
“And that’s why we want to work more closely together.
“And today I’m so glad that we’ve agreed the reciprocal access agreement between our armed services.”
Mr Kishida’s visit was marked with a guard of honour and an RAF flypast over Horse Guards Parade in central London.
Before holding talks in No 10 on Thursday, the two leaders stood on a dais as they witnessed a Voyager and two Typhoon fighter jets soar over St James’ Park and the parade ground.
Mr Kishida was then invited in Japanese by the captain of the Nijmegen Company, Grenadier Guards, to inspect the troops.
After the spectacle, Mr Johnson and Mr Kishida headed to Downing Street where the British leader announced that a military accord has been struck.
Downing Street officials said the cooperation agreement will boost the UK’s commitment to the Indo-Pacific and further safeguard global peace and security, and build on the already close collaboration on defence and security technology between both nations.
To boost UK-Japanese trade, Mr Johnson confirmed that former Cabinet minister Greg Clark, Tory MP for Tunbridge Wells, will be the UK’s new trade envoy to Japan.
The Japanese premier, speaking with a translator, thanked Mr Johnson for the “warm welcome”, noting that he had made time despite local elections taking place in the UK.
He told the Prime Minister he looks forward to a “very fruitful discussion” on the London-Tokyo bilateral relationship, as well as on Ukraine and global affairs.
Following their talks, a Downing Street spokeswoman said: “Both leaders agreed that Russia’s barbaric invasion marked the end of the post-Cold War period and had major implications for wider international stability.
“Security in the Euro-Atlantic and Indo-Pacific regions was indivisible, they agreed, and the G7 leaders said democracies around the world needed to stand in unity against authoritarian regimes.
“Discussing the recent ballistic missile launch by North Korea, the Prime Minister condemned the provocative actions and said the UK stood shoulder-to-shoulder with Japan and our Indo-Pacific allies.
“The Prime Minister praised the new in principle Reciprocal Access Agreement, an idea that was first raised between the leaders when they were foreign ministers, and said it was yet another symbol of the deepening relationship between the UK and Japan.
“On the UK’s Future Combat Air System (FCAS), both leaders agreed the UK and Japan were making significant progress, and the Prime Minister welcomed Prime Minister Kishida’s view that the project could become the cornerstone of the UK-Japan bilateral relationship.”
The spokeswoman added: “The leaders also agreed to deepen their research and innovation ties to develop cutting edge technologies of the future.
“The Prime Minister added that he hoped the two countries should continue to use their technology prowess and investment to develop more renewables to support energy security across the world.”
In a speech to City of London bosses at the Guildhall last night, the Japanese prime minister said: “History has proven that Great Britain has prospered through its connections with the world. Today, for Great Britain, that means above all being a major centre of international finance, with the City at its heart.
“This resonates with Japan, which is also a maritime nation.”