The alliance between the US and the UK should be known as the "indestructible relationship", Boris Johnson has said after meeting US President Joe Biden for the first time.
He said he had "terrific" talks with Biden, who has travelled to Cornwall for the G7 summit of world leaders, reports the BBC.
The summit begins later, with vaccines and climate change on the agenda.
Johnson insisted the US president had not rebuked him over post-Brexit tensions in Northern Ireland.
However, Biden is said to have "deep concern" over the situation.
The UK PM was speaking to the BBC's political editor Laura Kuenssberg, after meeting Biden in Carbis Bay, Cornwall, on Thursday ahead of the G7 summit.
The summit will see the leaders of Canada, France, Germany, Italy, Japan, the US and UK gathering in person for the first time since the pandemic.
Ahead of the meeting, Johnson pledged the UK would donate more than 100 million vaccines to poorer countries in the next year, while Biden promised 500 million doses of Pfizer vaccines to 92 low and middle-income countries and the African Union.
The G7 nations are expected to collectively agree to provide a billion doses of Covid-19 vaccine in an effort to end the pandemic in 2022.