UK Edition
Boris Johnson and Joe Biden privately expressed astonishment at France's heated reaction to the Aukus pact, as the Prime Minister urged Emmanuel Macron, the French president, to "get a grip".
Mr Johnson and the US president are understood to have discussed their surprise at the fury from Paris when they met for talks at the White House on Tuesday.
On Wednesday, the Prime Minister deployed franglais as he told the French to "prenez un grip and donnez-moi un break" over the row – roughly translated as "get a grip and give me a break".
He later said he was "taken aback" by Mr Macron's response, which included withdrawing ambassadors from the US and Australia.
On Wednesday night, there were suggestions that the French could withdraw from Nato's integrated military command.
Speaking about the row, Mr Johnson said: "There are no easy ways of having these conversations. It's a very human thing to delay the frank conversation until the last possible moment. I don't know if anyone has been in that situation in their emotional life, but it's very human to put it off.
"Everybody has been a bit taken aback by the strength of the French reaction, and we all want to reach out to Paris and sort something out."
In spite of French opposition, plans are being pursued to deepen the three-way defence pact between Australia, the UK and the US beyond just nuclear submarines, with trade and intelligence two possible avenues.
There is a belief in parts of the UK Government that the French are over-exaggerating their anger for potential financial reasons.
Submarine contracts between France and Australia, worth tens of billions of pounds, were torn up when Canberra went in with the UK and US, with legal wrangling over compensation now expected.
Discussing the row with reporters as his four-day US trip neared its end, Mr Johnson appeared to liken the French anger to that seen at the end of a personal relationship.
On Wednesday, Mr Biden talked to Mr Macron for the first time since the Aukus pact was signed. After the conversation, the White House said France's ambassador to Washington, who had been recalled amid the rift, would be returning to the US capital next week.
A joint statement issued after the call suggests Mr Biden sought to defuse tensions with his French counterpart during their conversation.
"The two leaders agreed that the situation would have benefited from open consultations among allies on matters of strategic interest to France and our European partners," the statement read.
Mr Biden is expected to meet Mr Macron during a visit to Europe in late October. The French president may well see Mr Johnson around then, with the G20 gathering in Italy.
French government ministers have described Aukus as a "stab in the back" and Britain as a "fifth wheel" to America and Australia and a "vassal" of the US. Mr Johnson has in recent days declared the deal is not meant to be "exclusive" and that he remains full of "love" and friendship for France, stressing the importance of the relationship.
Yet it emerged on Wednesday that the Aukus deal, which helps Australia gain nuclear-powered submarines, could become much wider than it is now.
It is understood the UK and US are discussing whether to reach new deals within the three-way pact on intelligence, deterrence of threats, free trade and human rights.
Mr Johnson and Mr Biden are understood to have agreed that France will not be allowed to join the agreement despite the public insistence the deal is not exclusionary. Mr Johnson met Scott Morrison, the Australian prime minister, for a dinner in Washington on Tuesday night at which they discussed the importance of the pact.
It is possible that Mr Johnson, Mr Biden and Mr Morrison could hold future joint meetings and summits, though no new meetings have yet been agreed.
Conversations about the details of how to expand Aukus are ongoing and understood to be at an early stage. It means the three-way partnership could become an increasingly influential force in diplomacy. It is part of the UK's "tilt" to the Indo-Pacific.
The pact is widely seen as a way to counter the growing influence of China in the region, though Mr Johnson has tried to play that down in public comments.
In France, there was no official reaction to Mr Johnson's Franglais comments. In a sign that Mr Macron's government is feeling the heat over the submarine affair, Florence Parly, his defence minister, was briefly booed during an exchange with senators.
Meanwhile, the French president faced strident domestic opposition calls to leave Nato's integrated military command structure, which France rejoined in 2009 – some 43 years after Charles de Gaulle pulled the country out and evicted US military bases from France.
Asked whether France should remain in the integrated military command, Ms Parly this week told senators: "We are in the process of weighing up our options regarding our different partners."
Pascale Boniface, the director of the French Institute for International and Strategic Affairs, said: "If Emmanuel Macron gets something from the United States and manages to save face, the French will be grateful to him. If he gets nothing, it will be detrimental to him."
Mette Frederiksen, Denmark's prime minister, appeared to weigh against France on Wednesday by saying Aukus was not grounds for a transatlantic dispute. She said: "I think it is important to say, in relation to the discussions that are taking place right now in Europe, that I experience Biden as being very loyal to the transatlantic alliance.
"And I think in general that one should refrain from lifting some specific challenges, which will always exist between allies, up to a level where they are not supposed to be. I really, really want to warn against this."