Trump officials have told Sir Keir Starmer he must boost Britain’s military with “urgency, scale, and determination”, as the prime minister insisted he would fight on despite a major row over defence spending.

Sir Keir’s premiership was plunged into crisis once again after his defence secretary John Healey and armed forces minister Al Carns dramatically resigned on Thursday, accusing the prime minister of failing to properly fund the armed forces and keep Britain safe.

Sir Keir hit back, insisting defence spending was a priority and that he had taken the “difficult decisions” necessary to keep the country safe.

But the White House piled further pressure on Sir Keir with a dramatic invention that highlighted the White House’s concerns.

US under-secretary of war Elbridge Colby wrote on X: “The United Kingdom has an extraordinarily proud military history. It commands our respect.

“There is again a great need for more British military strength in this critical time. We urge the UK to meet that need with urgency, scale, and determination.”

The two resignations – alongside two ministerial aides – over the long-delayed Defence Investment Plan (Dip) arrive at a perilous moment for Sir Keir, whose premiership has looked increasingly fragile since May’s election results and ahead of a key by-election next week.

Speaking on Friday after the latest drama, Sir Keir admitted he must “turn things around” to remain prime minister and lead Labour into the next general election.

But he insisted defence spending was a priority, saying that he had taken the “difficult decisions” necessary to keep the country safe.

He told the BBC: “I don’t think we should plunge the country into the chaos of a leadership election.

“I don’t think it should happen, but if it does then I will fight,” he said.

“And let me just be clear with you. That’s not about personal vanity, it’s not about stubbornness. It’s out of a very deep sense of duty.”

Read More: US urges Starmer to boost UK military strength with ‘urgency’