The spectres of President Biden’s health, the potential return of Donald Trump and an undiplomatic rant by Mr Zelensky all loomed over the summit.

Until that moment, the US leader had been almost word perfect having spoken in every single session of the meeting.

Nato members believed they had done enough to “Trump-proof” the alliance, announcing that 23 of its 32 states had hit the spending goals of 2 per cent of GDP on defence, with more setting out plans to reach the figure.

And most importantly, Mr Zelensky was leaving Washington satisfied with the levels of support shown by Nato, despite not being handed a formal invitation to the alliance.

“The Americans had put in months of groundwork into preventing another ‘Vilnius moment’,” a second official said, referring to the Ukrainian’s president’s outburst at last year’s summit after being refused an invitation.

There was also a sense of frustration that this moment would dominate questions put to other leaders in their final press conference before heading home.

Sir Keir Starmer was asked no fewer than three times if he thought President Biden was up to the task of running for a second term in the White House.

The Prime Minister said the US leader should be “given credit” for his work at the Nato summit, in defence of his ally.

He would’ve preferred to have been able to boast of his own achievements at the gathering instead of being the receiving end of diplomatically tricky questions.