Is Donald Trump's threat to impose more tariffs on countries trying to block his plan to buy Greenland the last straw for the strained relationship with the UK?
Sir Keir Starmer is walking a diplomatic tightrope - on the one hand rebuking the president for his threats, while on the other reiterating the UK and US remain the closest of allies.
But could this mark a point of no return for the man once described as the 'Trump whisperer'?
Niall speaks to the UK's first national security adviser, Lord Ricketts, about the history of the alliance between the UK and the US and whether Sir Keir can successfully keep it intact, at this delicate moment in history.
Producer: Tom Gillespie
Editor: Mike Bovill
