A day after the Republican congresswoman Marjorie Taylor Greene declared “David Cameron can kiss my ass” over his references to the appeasement of Hitler in an article appealing to US lawmakers to pass a Ukraine funding bill, the UK foreign secretary returned to the theme. Stood alongside his Polish counterpart, Radosław Sikorski, another experienced politician recently recalled to high office, he said: “Today, two foreign ministers stand here just like in the 1930s, when we faced a similar challenge in the case of an aggressive dictator who tried to change the world by force and ignored the sovereignty and inviolability of other countries’ borders.” Ukraine, he said, was “a challenge for our generation”, adding that the last time a dictator in Europe was allowed to invade other countries, Poland suffered the greatest consequences. With a limited period in office and the stakes so high, Cameron is a man in a hurry, showing a determination to leave a mark during his second chance in government even at the risk of fluttering diplomatic dovecotes. Sikorski, who returned to office last year after the defeat of the rightwing populist Law and Justice party, had the confidence this week to challenge Donald Trump’s transactionalism when the likely US Republican presidential candidate shocked Nato states by saying he would be happy to see Vladimir Putin invade countries that did not meet the target of spending 2% of their GDP on defence. He said on Thursday, alongside Cameron, that stopping Russian imperialism was a basic condition for preserving freedom and the value system of the civilised world. Of Trump’s comments, he observed that Nato’s article 5 had been activated only once, after the 11 September 2001 attacks on the US. Poland had then committed itself to Afghanistan and “did not send the bill to Washington”, he said. Cameron, who with Sikorski appealed for the US Congress to adopt an aid package for Ukraine, is aware he is taking risks and potentially offending supporters of Trump. On Israel as well, he feels inclined to do what he describes as showing some leg – by proposing that the UK might recognise a Palestinian state before any negotiations on a two-state solution are complete. He has also become ever more blunt that he thinks Israel is in breach of international humanitarian law if it fails to provide food, water and fuel to those trapped in Gaza. Cameron was aware his article dispensed with some diplomatic niceties. By writing in the US Congress-focused newspaper the Hill, he wanted to reach his target audience, to urge them to do their duty by the transatlantic alliance. The reference to 1930s appeasement and his grandfather fighting in the second world war was some calculated additional spice. He believes there is a natural majority in the US Senate and House to provide the aid for Ukraine and feels it is legitimate for the UK to help try to unlock it. As to claims he is interfering in the domestic politics of the US, he says to accept that is to accept the thinking of American isolationists that the US can withdraw from the world without any consequence save fewer bills. It is not the first time he has made the argument. On his previous trip to the US he used an Aspen Security Forum to say he was “worried that we’re not doing to do what we need to do” on Ukraine, adding that he wanted to address the argument he had heard repeatedly in US political circles: “Why should we meet these challenges overseas when there are so many challenges at home?” The checklist was simple. Ukraine was not losing. Europe was pulling its weight and paying its fair share. The military objectives were clear. It was a good investment, indeed value for money. Ten per cent of the US defence budget used by the Ukrainians has destroyed half of Russia’s prewar assets. Ukraine’s defeat would leave only two people smiling: Putin in Russia, and Xi Jinping in Beijing. He finished by asking them to recognise that “European security is also American security”. It is an argument that pits him against Donald Trump, someone he had no dealings with as prime minister and is unlikely to have future dealings with if the Conservatives are defeated, as expected, in a general election this year. Although he shares Boris Johnson’s determination to support Ukraine, he has none of Johnson’s illusions that Trump is essentially a liberal New Yorker. The Congress vote and the threatened return of Trump play into a wider discussion in Europe about how it responds politically and militarily. It is a debate in which the naturally pro-European Cameron would like to play a role, including on boosting weapons production. Europe, for its part, is wondering if it will need to ask for the UK’s nuclear weapons to come to its defence in the event of a US pullout. A natural optimist who thought he could persuade voters to reject the isolationism of Brexit, Cameron admits the world has turned into a darker place since he left office in 2016, badly damaged by the misjudgment of staging an arguably unnecessary Brexit referendum. His staff are very aware that it is easy for any UK foreign secretary to watch the pages of history turn without leaving any mark on them. With probably less than 10 months left in office, and two massive world crises playing out, it requires him to move with a speed and pointedness that others might not. He also knows that as long as he makes no major mistakes, he has the confidence of a prime minister who has to focus on trying to win the next election. Rishi Sunak will not be attending the Munich Security Conference this weekend, unlike Cameron and the Labour leader, Keir Starmer. From Munich Cameron flies to the G20 foreign ministers’ meeting in Brazil where he hopes to take on the global south, and those that say the west has shown hypocrisy and double standards over Ukraine and Israel. Once the youngest prime minister since 1812, and never lacking in self-confidence, he hopes his experience in foreign affairs will help him navigate ending one war in Gaza and keeping another in Ukraine alive. It is likely to be a bumpy ride.