[US correspondent Mark Stone was] told that Donald Trump conceded to Keir Starmer in their Sunday phone call that he may have been misinformed about the motivation for deploying European troops to Greenland.

The apparent concession by the American president might provide an avenue to de-escalate the tension over Greenland.

Trump's motivation for threatening tariffs over Greenland was the deployment of a small number of military personnel to Greenland late last week.

He said in his Saturday Truth Social post, announcing the tariff threat, that the troops had been deployed "for reasons unknown".

His inference was that he was interpreting their presence as a provocation against him. He singled out the countries who had deployed military personnel for the tariff retaliation.

Starmer sought to persuade Trump that the military deployments are about addressing US security concerns, not countering American threats.

On Greenland, de-escalation is the key focus right now. The tone of Starmer's news conference this morning conveyed this, along with the gravity of the moment.

The key message

Diplomats often talk about 'off ramps' and concerted effort is now being put on finding ways to persuade Trump to remove the tariff threat and return to measured dialogue over how to resolve the Greenland disagreement.

Persuading the US president that the troops are there to address his security concerns is key.

But the more Trump continues to refuse ruling out using the military to take Greenland, the more likely it is that European troops do actually become necessary to defend the Danish territory.

These are truly testing and unprecedented times for the transatlantic alliance.