Lord David Cameron warned allies in the United Nations against “fatigue” and “compromise” over Russia’s war in Ukraine as he urged countries including the US to keep up support for Kyiv.
The UK Foreign Secretary said the world must “recognise the cost of giving up” in a speech in New York on the eve of the second anniversary of Moscow’s invasion.
European countries are struggling to find enough stock to send to Kyiv, and US help worth 60 billion dollars (£47 billon) is stalled over political differences in Washington.
Speaking at the UN general assembly on Friday, Lord Cameron said: “Two years on, I recognise some want a rethink. There is a sense of fatigue. There are other problems.
“A compromise might seem attractive. But this is wrong. We must recognise the cost of giving up.
“Putin has said there will be no peace until Russia’s goals have been achieved. And in his latest interview, he studiously avoided confirming he was satisfied with the land seized from Ukraine at present.”
The Foreign Secretary added: “This is not a man seeking compromise. Rather, this is a neo-imperialist bully who believes that might is right.”
Lord Cameron also renewed his appeal to US politicians to pass a multi-billion-dollar aid package including support for Ukraine, telling reporters during his visit: “This is fundamentally about US security too.”
Saturday marks two years since the Kremlin launched its full-scale attack on Ukraine, starting the biggest incursion in a European country since the Second World War.
Kyiv has kept up strikes from behind the front line in recent weeks but moved to a defensive posture amid critical shortages on the battlefield.
Lord Cameron, who was UK prime minister during Russia’s annexation of Crimea in 2014, started his speech by saying “the lesson of this history is clear: if we do not stand up to Putin, he will be back for more.”
“Putin tries to claim that Russia is fighting not against Ukraine, but against the whole of the west,” he told the assembly.
“He claims we are somehow out to dismember Russia. That is the central lie of this war.”
Victory for the Moscow leader would not end with Ukraine, Lord Cameron said.
“Putin could easily apply his distortions of history elsewhere, such as Moldova or the Baltic States,” he told allies.
“And others will be emboldened to turn to fighting when it suits them. No country with a large, aggressive neighbour would be safe.”
His speech came after Russian ambassador to the UN Vassily Nebenzia falsely suggested that Moscow had not started the war.
Lord Cameron called earlier this month for US lawmakers to pass a bill including support for Ukraine, likening any refusal to do so with appeasement of Hitler in the 1930s.
The intervention drew the ire of right-wing congresswoman and Donald Trump ally Marjorie Taylor Greene, who told him to “kiss my ass” and “worry about his own country”.
The bill has passed through the Senate but faces an uphill battle in the House of Representatives, where hard-line Republicans aligned with Republican presidential front-runner Mr Trump oppose the legislation.
Lord Cameron went further on Friday, directly comparing the Russian president and his inner circle to “Nazis” thinking they could invade a country and “the world would look away”.
Kyiv officials have pleaded with western partners to accelerate delivery of military aid so its forces can hold out against an emboldened Moscow.
Ukrainian forces withdrew from the strategic eastern city of Avdiivka at the weekend, where they had battled a fierce Russian assault for four months despite being heavily outnumbered and outgunned.