French President Emmanuel Macron has said he convinced US President Donald Trump not to withdraw troops from Syria and instead commit “for the long term”.
Earlier this month, Mr Trump declared that the US would “be coming out of Syria very soon”.
On Saturday, joint US, UK and French strikes targeted Syrian government sites in response to an alleged chemical weapons attack.
Mr Macron said he also persuaded Mr Trump to keep the strikes limited.
The pair, who are reported to have a friendly relationship, spoke multiple times in the days before the military action was taken.
After Mr Macron’s comments, White House spokeswoman Sarah Sanders said: “The US mission has not changed – the president has been clear that he wants US forces to come home as quickly as possible”.
But she added that the US was “determined to completely crush” the Islamic State group and prevent its return.
Announcing the strikes in an address to the nation on Friday evening in Washington, Mr Trump insisted: “America does not seek an indefinite presence in Syria – under no circumstances.”
The US has about 2,000 personnel on the ground in eastern Syria supporting an alliance of Kurdish and Arab militias called the Syrian Democratic Forces (SDF).
Speaking in a live TV interview, during which he was grilled on several subjects, Mr Macron said: “Ten days ago, President Trump was saying ‘the United States should withdraw from Syria’. We convinced him it was necessary to stay for the long term.”
In telephone calls with Mr Trump, he also said he “persuaded him that we needed to limit the strikes to chemical weapons [sites], after things got a little carried away over tweets”.
A tweet from Mr Trump last week about US missile strikes on Syria had read: “Get ready, Russia, because they will be coming, nice and new and ‘smart’. You shouldn’t be partners with a Gas Killing Animal who kills his people and enjoys it!”
The French president appears to have struck up a strong relationship with his US counterpart and this month will be afforded the first formal White House state visit of the Trump presidency.
Mr Trump attended France’s Bastille Day parade last year.
Mr Macron insisted the Western allies had “complete international legitimacy to act” in Syria. He said the allies had clear proof there had been a chemical attack in the town of Douma near Damascus on 7 April and that the Syrian government was responsible. Syria vehemently denies this.
Mr Macron said he told Russian President Vladimir Putin directly that Russia – which backs the Syrian government militarily – was complicit.
“They have not used chlorine themselves but they have methodically built the international community’s inability to act through diplomatic channels to stop the use of chemical weapons,” he said.
He said the military strikes early on Saturday had been “perfectly carried out” but were not a declaration of war on Syria.
The wave of strikes had represented the most significant attack against President Bashar al-Assad’s government by Western powers in seven years of Syria’s civil war.
Mr Macron said he still wanted dialogue with all parties, including Russia, to try to find a political solution and would go ahead with a planned trip to Moscow next month.
His marathon interview on French broadcaster BFMTV lasted nearly three hours – and #MacronBFMTV was a top trend on Twitter late on Sunday evening.