The prime minister has vowed not to choose between allies of the UK in a speech on foreign policy.
Attacking the Conservatives for having “turned their back on the world”, Sir Keir Starmer said his government would instead strengthen ties with both the US and the EU.
Sir Keir also stressed the current “dangerous times”, saying stability was essential for growth, so the UK must continue to back Ukraine against Russia “as an erratic, increasingly desperate aggressor”.
He added: “There is no growth without security – and no security without alliances.”
Speaking at the Lord Mayor’s Banquet in London’s Guildhall, an annual event held by the City of London Corporation and where the PM traditionally speaks on international issues, Sir Keir set out how the UK would now “stand tall on the world stage”.
“Against the backdrop of these dangerous times, the idea that we must choose between our allies, that somehow we’re with either America or Europe, is plain wrong,” he said.
“I reject it utterly. Attlee did not choose between allies. Churchill did not choose.
“The national interest demands that we work with both.”
Sir Keir said he told President-elect Donald Trump during their meeting in New York in September that the UK “will invest more deeply than ever in this transatlantic bond with our American friends in the years to come”.
He also repeated his commitment to “rebuild our ties with Europe too”.
Sir Keir insisted it is “deeply in our self-interest” to support Ukraine against Russian president Vladimir Putin because “the future of freedom in Europe is being decided today”.
The UK is now “determined to fight harder on the world stage for our national interests and ready to dig deeper to defend them”, he said, because a win for Putin would damage “our own security, stability and prosperity”.
“So we must continue to back Ukraine and do what it takes to support their self-defence for as long as it takes,” he said.
Supporting allies was what former prime ministers Clement Attlee and Winston Churchill had done, he said, adding that he thought of the Attlee government of 1945 and its ambition to build “a country fit for heroes”.
“And they saw that maintaining our strength abroad gave us the foundation to succeed at home. That is as true today as it was then,” he said.
Now was the time, Sir Keir said, to “strengthen our security as the bedrock on which the economy rests – and the ultimate guarantor of everything we hold dear”.
However, Conservative Party co-chair Nigel Huddlestone said it was Sir Keir’s government that had “set our country back” since Labour took power five months ago.
He said: “From driving business confidence to near-record lows, working people punished with a jobs tax, growth projections slashed, and a dash to surrender British interests overseas – it’s no wonder he’s been forced into a desperate reset.”