Japanese Prime Minister Kishida Fumio is meeting with his British counterpart Rishi Sunak in London on Wednesday.
Britain is the third leg of Kishida's tour of five Group of Seven nations. His trip comes before Japan hosts the G7 summit in Hiroshima in May.
During the meeting with Sunak, Kishida plans to call for unity among the G7 members to hold a successful summit amid global challenges such as the conflict in Ukraine as well as food and energy issues.
Kishida is also expected to tell Sunak that Japan is working to bolster its defense capabilities to uphold a free and open international order.
The two leaders are likely to reaffirm a further advancement of bilateral security cooperation.
Kishida and Sunak are expected to sign a Japan-UK Reciprocal Access Agreement following their summit.
The agreement is aimed at facilitating joint exercises and other operations between Japan's Self-Defense Forces and the British military.
The British government says the country will be the first European nation to have an agreement of this kind with Japan. It called the deal the most important defense treaty between the two countries since 1902. Japan and Britain signed the Anglo-Japanese Alliance in that year.
Prime Minister Sunak said the agreement cements the two countries' commitment to the Indo-Pacific and underlines their joint efforts to bolster economic security, accelerate their defense cooperation and drive innovation.
He added, "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."