US President Joe Biden has described relations with the UK as “rock solid” during talks in London with Prime Minister Rishi Sunak.
Mr Biden said he “couldn’t be meeting a closer friend and a greater ally”. Mr Sunak hailed the UK and the US as “two of the firmest allies” in Nato.
They also discussed a US move to give Ukraine controversial cluster bombs to defend itself from Russia’s invasion.
Ukraine’s membership bid will be high on agenda at Tuesday’s Nato summit.
All 31 Nato members attending the summit in Vilnius, Lithuania, agree that Ukraine cannot join the military alliance during the war – amid fears this would lead to a direct conflict with Russia.
Ukrainian President Volodymyr Zelensky has himself said he does not expect Kyiv to join the bloc until after the war – but he wants the summit to give a “clear signal” on Ukraine’s bid.
Several Nato members in Eastern Europe are pressing for a fast-track membership for their neighbour – but others, including the US, are seen as more hesitant, fearing this could lead to a direct conflict with nuclear-armed Russia.
Referring to the US pledge of cluster bombs for Ukraine – something which caused unease among Nato allies – Mr Sunak’s official spokesman said it “was a difficult choice for the US”.
But the spokesman added that the decision had been “forced on them by Russia’s war of aggression”.
The weapons have been banned by more than 100 countries, including the UK, because of the danger they pose to civilians.
The spokesman said Sunak was upholding the UK’s requirements under an international convention banning the weapons.
The US says it has received Ukraine’s reassurance that the munitions will not be used in Russia or in urban areas.
President Biden also held separate talks on Monday with King Charles at Windsor Castle – the pair’s first meeting since the King was formally crowned in May.
Mr Biden received a royal salute and listened to the US national anthem performed by the Welsh Guards before entering the castle for the talks.
