Britain’s most senior military commander has called on the US to “stay strong, stick together, and see through” conflicts in Ukraine and the Middle East as he appealed against future American isolationism on a trip to Washington DC. Adm Sir Tony Radakin said at a conference he believed “the world is undeniably becoming more dangerous” and invoked memories of D-day to justify potential future US engagement in struggles against authoritarian regimes. Citing next month’s 80th anniversary of the invasion of Normandy, Radakin said the battle had involved “young men” from the US, UK and other allied countries, fighting on the beaches with a sense of purpose to defeat Adolf Hitler. “They were to see through what Gen Eisenhower termed ‘the elimination of Nazi tyranny over the oppressed peoples of Europe, and security for ourselves in a free world’,” Radakin said. “In all the great conflicts of the 20th century, the west prevailed because we understood what was at stake.” The speech at the Ash Carter Exchange came a few weeks after the US Congress voted through fresh military aid worth $61bn to Ukraine and $14bn to Israel after a hiatus of several months, though he did not refer to it directly. Radakin acknowledged the battlefield situation in Ukraine had deteriorated for the defenders, though he did not directly link it to the protracted hold-up in funding caused by Donald Trump-aligned Republicans in the House who were sceptical about the value of further military aid to Kyiv. This year, having rebuffed Ukraine’s summer counteroffensive, the Russian army “has been able to make modest tactical gains”, Radakin said. Territory in the east had been captured slowly, he said, and “at even higher cost in men and material and to the national economy of Russia”. The west, if it acted, had the capacity to support Ukraine with “millions of rounds of ammunition, thousands of drones, hundreds of tanks and armoured vehicles”, he said, while Russia would have to “twist its economy out of shape to sustain the war”, widely expected to last into 2025. Ukraine, the Middle East and China were interlinked by “a battle of ideas”, Radakin said, between “an authoritarian and belligerent Russia and a dynamic, democratic Ukraine” and “between a reckless Iran and its terrorist network on one side, and the responsible nations of the Middle East on the other”. He warned of a split “between a China that believes it can dominate and coerce, and those nations that share a commitment to an international system that is open and free” – an effort to link future funding of Ukraine with more established US concerns about the security of Israel and the rising power of Beijing. The UK, he said, had joined with the US, France and others last month in helping Israel repel a major missile and drone attack from Iran “to prevent the conflict with Hamas escalating into all-out war” – though his only explicit reference to the crisis in Gaza as Israel stepped up its attacks on Rafah was to say “international aid is coming”. Responding to “a more combative world” required statecraft, Radakin told his audience in the US capital, forming closer partnerships with allied countries and being willing to take military action if needed to uphold “the rules and values” shared by the west. “The task now is to stay strong, stick together, and see it through,” he said.