Prime Minister Rishi Sunak flew in to Washington late Tuesday lobbying for Britain to take a lead role in regulating artificial intelligence, after a dire warning of the technology's existential dangers.
Sunak will meet President Joe Biden on Thursday for a White House summit, pledging unstinting support for Ukraine after Russia was accused of blowing up a major dam to thwart an apparent counter-offensive.
But while the United States and Britain are inching closer on giving Ukraine air support, and on a robust approach to China, Sunak faces a harder sell with Biden about the UK's post-Brexit relevance elsewhere.
The need for a coordinated response on AI was underlined by Downing Street task force advisor Matt Clifford, who warned the chances of the fast-learning systems wiping out humanity within two years were "not zero."
Interviewed on TalkTV, he said the world needed "to regulate them on a global scale, because it's not enough I think to regulate them nationally."
Sunak wants a future global AI regulator to be based in London, according to sources, arguing Britain has the requisite expertise and size of tech sector.
But it is pushing uphill as the United States talks directly to the European Union about AI regulation, to build on a pledge by G7 leaders including Sunak in Japan last month.
- 'Battlefield advantage' -
En route to Washington, the prime minister announced cumulative US investment of more than £14 billion ($17 billion) into Britain -- although some of that has already been deployed.
Underlining the US-UK military alliance at the heart of NATO, Sunak said their economic relationship should also be deployed to defend Western democracy.
"By combining our vast economic resources and expertise, we will grow our economies, create jobs and keep our people safe long into the future," said the prime minister, a wealthy former banker who studied in the United States and retains a property in California.
"Just as interoperability between our militaries has given us a battlefield advantage over our adversaries, greater economic interoperability will give us a crucial edge in the decades ahead."
Sunak is pushing for US relief to UK carmakers, via greater access to critical minerals used in electric batteries, after Biden's Inflation Reduction Act offered vast subsidies to US companies.
On the NATO front, Sunak has been talking up Defence Secretary Ben Wallace as the Western alliance seeks a new secretary-general at a summit in Lithuania next month.
"I have absolutely zero doubt that the war in Ukraine will be a prime issue of discussion" in Thursday's summit, US National Security Council spokesman John Kirby said.
"And the Brits have been right there -- literally at the fore in terms of helping Ukraine," he added.
"I have no doubt that they'll talk about ways in which we can work together going forward."
- No home run -
On Wednesday, Sunak will lay a wreath at Arlington National Cemetery outside Washington before heading to Capitol Hill for talks with leaders in Congress.
He will then watch the Washington Nationals play the Arizona Diamondbacks for the second annual "UK-US Friendship Day", marking 238 years of diplomatic relations.
But Sunak, a keen cricketer, has ducked the opportunity to throw the ceremonial first pitch at the baseball game -- sparing his blushes if the throw goes astray in front of tens of thousands.
After transatlantic disputes over trade and Northern Ireland, Sunak hopes to score better with Biden than his controversial predecessors Boris Johnson and Liz Truss.
"The relationship is very strong on the fundamentals: defense, security, developing policy on China," commented Leslie Vinjamuri, director of the US and Americas Programme at the Chatham House think tank in London.
But on specifics such as AI and trade, Biden is unlikely to give much away heading into a crunch election year, she told AFP.