Sir Keir Starmer will accuse parties like Reform UK and the Greens of being “soft on Russia”, “weak on NATO” and more likely to leave the nation divided and defeated.
The prime minister will further risk the wrath of Nigel Farage and his Brexiteers by saying that the UK is no longer the “Britain of the Brexit years” in a call for European unity to defend the continent from Russian aggression as the US steps back.
The comments will be delivered in a speech to global leaders at a security summit in Munich on Saturday.
However, despite the strong language, he is not expected to announce any plans to speed up a pledge to increase core defence spending from just over 2.3% to 3.5% of GDP by 2035.
Military officers privately concede this near-decade-long timeline, despite being agreed by all NATO allies, is far too slow and unambitious, given the scale of the threat posed by Russia and the need for the European side of the transatlantic alliance to do much more to defend itself as Donald Trump moves US assets away from the continent to focus on other priorities.
In an extraordinary attack on Reform UK and the Green Party, Sir Keir underlined the need to explain to the public why it is important to invest in rebuilding Britain’s defences.
“Because, if we don’t, the peddlers of easy answers on the extreme left and the extreme right are ready. They will offer their solutions instead,” he will say, according to excerpts from the speech released in advance.
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“It’s striking that the different ends of the spectrum share so much. Soft on Russia and weak on NATO – if not outright opposed.
“And determined to sacrifice the longstanding relationships that we want and need to build, on the altar of their ideology.
“The future they offer is one of division and then capitulation. The lamps would go out across Europe once again. But we will not let that happen.”
A spokesperson for Reform UK fought back in a statement: “This is a speech from a weak prime minister on the verge of being hounded out of office by his own party. This is a man that refuses to find the money to increase defence spending and is making our country weaker and less secure.
“Reform UK believes our priority should be rebuilding our armed forces, properly funding defence to at least 3.5% of GDP, standing up to China and Russia and strengthening our bilateral relationships.”
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The Starmer government is looking to forge closer relations with European Union allies in procuring military equipment, such as missiles, warplanes and drones – a strengthening of ties that were badly strained after the UK voted to leave the bloc a decade ago.
“We are not the Britain of the Brexit years anymore,” the prime minister is expected to say.
“Because we know that, in dangerous times, we would not take control by turning inward – we would surrender it. And I won’t let that happen.
“There is no British security without Europe, and no European security without Britain. That is the lesson of history – and it is today’s reality too.”
The comments triggered an instant backlash from the Conservatives.
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Dame Priti Patel, the shadow foreign secretary, said: “Keir Starmer has a habit of handing away sovereignty and now he is once again rolling the pitch for greater EU integration and less control for the UK.
“Britain is uniquely placed to help bring the US and Europe together, ensuring NATO is as strong as possible. We must not be overdependent on America, but neither should we offer Europe a blank cheque, prepared to accept any and all costs as Labour are.”
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In what has become the biggest public annual gathering on European security, the three-day Munich Security Conference is also bringing together Marco Rubio, the US secretary of state, as well as leaders of European allies such as Germany and France, plus delegates from across the world, including China’s foreign minister.
Volodymyr Zelenskyy, the Ukrainian president, is also present and is due to give his speech to the conference as well on Saturday, with efforts still under way, led by the US, to secure a peace deal between Kyiv and Moscow even as Russia’s full-scale war is about to enter its fifth year.
Mindful of the need to keep Washington close, Sir Keir is expected to say that the US remains an indispensable ally – but that the UK and Europe need to be able to operate militarily with more independence.
“I’m talking about a vision of European security and greater European autonomy that does not herald US withdrawal but answers the call for more burden sharing in full, and remakes the ties that have served us so well,” he is expected to say.
