British Prime Minister Boris Johnson and US President Joe Biden was expected to agree a new version of the "Atlantic Charter" aimed at leading the world's pandemic recovery and bolstering ties.
The agreement comes as the leaders hold their first face-to-face talks on Biden's first overseas trip of his presidency.
The new pact, modelled on the 1941 accord signed by Winston Churchill and Franklin D. Roosevelt, aims to emulate the original accord, which shaped the post-war world order by promoting democracy, free trade and opportunity.
The 2021 charter will cover everything from global defence and security to rebuilding from coronavirus and curbing climate change, according to Johnson's Downing Street office.
In remarks released ahead of the meeting, Johnson said close cooperation between London and Washington "will be crucial for the future of the world's stability and prosperity".
Johnson greeted Biden yesterday in the English seaside resort of Carbis Bay, ahead of the G7 summit. The US president touched down in Britain late Wednesday ahead of the three-day gathering.
"It's gorgeous, I don't want to go home," Biden said of the seaside view as he walked with First Lady Jill Biden, Johnson and Johnson's wife Carrie.
The two leaders will hold talks before the summit begins today.
The new Atlantic Charter will outline eight areas where the transatlantic allies resolve to work together based around their "enduring values", Downing Street said.
They include addressing threats posed by cyberattacks, climate change and biodiversity loss, as well as scaling up joint pandemic recovery work such, including genomic sequencing and variant assessments.
The two leaders are also set to agree several new policy priorities to underpin the charter, spanning travel, trade, post-Brexit issues in Northern Ireland and defence.
Analysts say Europe's bitter dispute with Britain over post-Brexit trade rules for Northern Ireland will haunt Johnson's G7 summit.
Ahead of the meet with Johnson, Biden camp warned Britain for imperilling the delicate peace in Northern Ireland.
"President Biden has been crystal clear about his rock-solid belief in the Good Friday Agreement as the foundation for peaceful co-existence in Northern Ireland," White House national security adviser Jake Sullivan told reporters aboard Air Force One.
"Any steps that imperil it or undermine it would not be welcomed by the United States," said Sullivan, who declined to characterise Johnson's actions as imperilling the peace.
European Commission president Ursula von der Leyen confirmed yesterday that she would bring up the row when she and fellow EU chief Charles Michel meet Johnson.