UK Prime Minister Rishi Sunak and Japanese leader Fumio Kishida are set to sign on Wednesday what the British government says will be the most significant defence deal between the two nations in more than a century.
The UK and Japan will allow forces to be posted in each other’s countries.
Downing Street is calling the agreement the most important defence treaty between London and Tokyo since 1902 and it will make the UK the first European country to have reciprocal access with Japan.
The pact is part of the UK’s defence and foreign policy lean towards the Indo-Pacific region after an integrated review in 2021 recognised the growing influence of China in the area.
It has been years in the making, with former prime minister Boris Johnson agreeing in principle to a deal in May during Mr Kishida’s first official visit to Britain.
Mr Sunak said the accord would “cement the UK’s commitment to the Indo-Pacific” and bolster economic security.
Officials said the agreement would allow both forces to plan and deliver larger and more complex military exercises and access.
“In the past 12 months, we have written the next chapter of the relationship between the UK and Japan, accelerating, building and deepening our ties," Mr Sunak said.
“We have so much in common: a shared outlook on the world; a shared understanding of the threats and challenges we face; and a shared ambition to use our place in the world for global good, ensuring our countries prosper for generations to come.
“This reciprocal access agreement is hugely significant for both our nations.
"It cements our commitment to the Indo-Pacific and underlines our joint efforts to bolster economic security, accelerate our defence co-operation and drive innovation that creates highly skilled jobs.
“In this increasingly competitive world, it is more important than ever that democratic societies continue to stand shoulder to shoulder as we navigate the unprecedented global challenges of our time.”
Mr Kishida’s visit to London is part of a whistle-stop tour to five Group of Seven nations, marking Japan taking on the rotating presidency of the group for 2023.
His trip, in which he will visit France, Italy, the UK, Canada and finally the US in five days, comes as Japan breaks from its post-war restraint to take on more offensive roles, with an eye towards China.
Japan announced last month it had adopted security and defence reforms, including a counter-strike capability that breaks from a defence-only principle that had been in place since its Second World War defeat.
While at the Tower of London, Mr Sunak and Mr Kishida will view Japanese armour on display.
It was presented to King James VI in 1613 by Shogun Tokugawa Hidetada of Japan.
It was given to the king to mark the first trade agreement between England and Japan.
Signing the deal at the tower will come weeks after the UK and Japan agreed, along with Italy, to develop the next generation of combat fighter jets under the Global Combat Air Programme.
Last month, the UK and Japan also launched a new digital partnership to strengthen co-operation across cyber resilience, online safety and semiconductors.
The leaders are also expected to discuss trade and the G7 response to Russia’s invasion of Ukraine, with the conflict approaching its first anniversary.
