Joe Biden accidentally called Rishi Sunak “Mr President” as the two met in the White House.
The US President has previously twice mispronounced Mr Sunak’s name on other occasions amid continuing concerns over his health.
But the President also hailed the strenght of the Special Relationship.
The Prime Minister and US president spoke in the Oval Office about the “brutal invasion” of Ukraine and the technological revolution sweeping the world.
Mr Biden – who inadvertently described the Prime Minister as “Mr President” – told reporters the special relationship was in “real good shape”.
READ MORE: Sunak’s problems hightlighted by US politicians struggling to remember his name
“Together, we are providing economic and humanitarian aid and security systems to Ukraine in their fight against a brutal invasion from Russia,” the president said.
“The global economy is undergoing the greatest transformation that has occurred since the industrial revolution,” he added.
Mr Biden told Mr Sunak: “We’re going solve all the problems of the world in the next 20 minutes.”
He referenced Winston Churchill’s wartime visit to the White House and Mr Sunak said: “It’s daunting to think of the conversations that our predecessors had in this room when they had to speak of wars that they fought together, peace won together, incredible change in the lives of our citizens.
“And again, for the first time in over half-a-century, we face a war on the European continent.
“And as we’ve done before, the US and the UK, have stood together to support Ukraine and stand up for the values of democracy and freedom and make sure that they prevail, as I know we will.
“But also I completely agree with what you said, our economies are seeing perhaps the biggest transformation since the industrial revolution, as new technologies provide incredible opportunities, but also give our adversaries more tools for harm.”
Before their meeting, Mr Sunak announced the UK would host the first global summit on AI safety.
The summit, which would be held in the autumn, would consider the need for international co-ordinated action to mitigate the risks of the emerging technology.
The meeting is seen as a sign in a turning point for UK/ US relations particularly with Biden and the Democrats amid acrimony following Brexit.
Trade talks with the US government have yet to start again but yesterday both the Republican House Speaker Kevin McCarthy and Democrat Senate majority leader Chuck Schumer both expressed eagerness for the UK and US to have a formal trade deal.
Mr Sunak’s pursuit of a deal on AI is a way of broaching a wider deal in the future.
Relations have calmed since Mr Sunak brokered the Windsor Framework agreement with the EU on Northern Ireland.
President Biden had made it clear that no progress with UK/ US relations could be made until that was resolved.
