US President Joe Biden and British Prime Minister Rishi Sunak said their countries would partner on advanced technologies, clean energy and critical minerals as they strengthen a historical security alliance.
Biden and Sunak signed the "Atlantic Declaration," which Sunak described as a first-of-its-kind economic partnership on artificial intelligence and other economic and commercial relations.
The signing of the deal came as the British leader made an official visit to the White House.
Britain and the US's long-standing military and security partnerships have strengthened amid Russia's war in Ukraine and China's more aggressive posture in Asia, but a much-hoped-for free trade agreement has not materialised.
"Our economic partnership is an enormous strength - a source of strength that anchors everything that we do together," Biden told reporters.
"I know some people have wondered what kind of partner Britain would be after it left the EU," Sunak said, announcing the new deal.
"I'd say, judge us by our actions. We're as committed to our values as ever, as reliable of an ally as ever, as attractive an investment destination as ever," he added.
Britain exited the EU on January 31, 2020.
Sunak, who took office last October after a period of unprecedented political instability in the country, has pushed to strengthen trading ties between the US and UK, despite the bleak prospects for a post-Brexit free trade agreement.
Biden will ask Congress to rewrite the Defense Production Act to treat British suppliers with some of the favorable terms afforded domestic suppliers.
Biden and Sunak also launched negotiations on a critical minerals agreement that could allow electric vehicle minerals produced in Britain to count towards tax credits for clean vehicles offered under Biden's Inflation Reduction Act.
That law's made-in-America bent has frustrated US allies from London to Seoul, and Biden is holding separate talks on the topic with EU leaders.
Biden and Sunak fielded questions at the joint news conference after their meeting, an opportunity not afforded to every world leader who visits the White House.
The two leaders last met in Hiroshima, Japan, at the Group of Seven summit last month. They also met in Belfast in April and in San Diego in March at a trilateral event marking the defense partnership of the US, Australia and Britain.
Their latest discussions touched on artificial intelligence safety, Sunak told reporters, saying Britain would host the first summit on the issue this autumn to discuss how the risks of AI can be mitigated through internationally coordinated action.
In the absence of a bigger trade deal, Britain has cemented deals with individual states and is hoping to reach other such "targeted agreements."
