Ministers have been pleading with Donald Trump not to attack Sir Keir Starmer over his social media ban.
Both world leaders are currently in France for the G7 summit, which is thought to follow a long-winded lobbying campaign from Labour's top brass to avoid backlash from the White House.
Ministers said they have spent weeks trying to reassure US officials the social media ban was not specifically aimed at US tech firms.
It limits access to platforms including X, YouTube, Facebook, Snapchat and TikTok for under-16s.
All but X and TikTok are American-owned, and all are headquartered in the US.
The President has previously threatened to hammer Britain with a "big tariff" if the Government does not drop its digital services tax.
One person involved in the lobbying effort told The Guardian ministers took a three-pronged approach to "engage the companies, pre-brief the administration and myth bust in the media".
"This is about protecting children in Britain, not taking on US tech," they said.
But the owner of X - and the world's first trillionaire - Elon Musk, said on his platform: "This censorship law is a wolf in sheep's clothing. The real goal is to enable the UK Government to track everyone."
He went on to brand the UK a "police state".
Donald Trump has previously threatened to Britain with a 'big tariff' if it did not lift a digital services tax
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Sarah Rogers of the State Department, meanwhile, has led American fury at Labour's internet clampdowns.
She recently revealed the US Government's new "free speech portal" was being flooded by Britons complaining about censorship at home.
The newly-established freedom.gov website - designed to bypass to bans on "hate speech" in places abroad - has been inundated with complaints from British users.
Sir Keir said he had last spoken to Mr Trump on Saturday - before announcing the ban.
At the G7, he is expected to discuss the issue of the social media clampdown alongside "many other issues" which other leaders are interested in.
MORE ON THE SOCIAL MEDIA BAN:
Sir Keir Starmer has said he spoke to Donald Trump on Saturday and expected to discuss the social media ban
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One such leader, Emmanuel Macron, thanked Britain "for joining the movement" on banning social media yesterday.
Earlier this week, fellow G7 member Canada announced its own proposed crackdown which would regulate AI chatbots and curtail "harmful content" online, creating a regulator to ensure tech firms comply.
And in January, France passed a Bill in both chambers to ban social media for those under 15, set to be implemented before the start of the school year in September.
The meeting marks the first time Sir Keir will meet Mr Trump face-to-face after the US President's infamous "no Churchill" jab, though he still has yet to weigh in on the social media ban.
However, the White House calmly voiced its opposition to it last week in a note released through the American Embassy in London.
Sir Keir Starmer has denied any suggestion the ban was 'rushed'
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It said Washington favoured "narrowly targeted requirements primarily with respect to pornographic and adult commercial content, rather than broad social media bans".
That stance was also submitted to the British Government's ban consultation.
Back in the UK, critics of the ban, including Ian Russell, the father of a 14-year-old who killed herself after viewing harmful content online, said the social media ban was "politically expedient" and told The Telegraph it was a "rush job".
Mr Russell has called for the Government to tackle specific suicide, self-harm and eating disorder content on platforms, rather than a blanket ban.
Sir Keir denied any suggestion it was "rushed", with the consultation "gone carefully through", but added he would continue to work with Mr Russell on the issues he raised.
A spokesman for Meta, which owns Facebook and Instagram: "As we've seen in Australia, bans risk isolating teens from online communities and information, and driving them to unregulated alternatives that lack built-in protections and parental controls."
A spokesman for YouTube said: "Blanket bans push kids out of such curated, supervised, beneficial experiences and towards anonymous, less safe services."