In an interview with US television on Sunday, Boris Johnson characterised Donald Trump’s impeachment and acquittal on a charge of inciting insurrection against his own government as “toings and froings and all the kerfuffle”. The prime minister’s words jarred with those of Joe Biden. In a statement on Saturday night, the new president said: “This sad chapter in our history has reminded us that democracy is fragile.” Five people died as a direct result of the attack on the US Capitol by Trump supporters, who the president told to “fight like hell” in his attempt to overturn election defeat, on 6 January. In the former president’s second impeachment trial, House prosecutors showed chilling footage of lawmakers being hustled to safety by Capitol police. Members of the pro-Trump mob chanted “hang Mike Pence” as they searched for Trump’s vice-president. Some erected a gallows outside the Capitol. Johnson has condemned the Capitol attack. On Sunday he appeared on CBS’s Face the Nation. Asked what signal the acquittal of a president who stoked such violence while casting doubt on a free election would send to the rest of the world, he said: “The clear message that we get from the proceedings in America is that after all the toings and froings and all the kerfuffle, American democracy is strong and the American constitution is strong and robust.” Biden is not so sure. Democracy “must always be defended”, he said, adding: “We must be ever vigilant … each of us has a duty and responsibility as Americans, and especially as leaders, to defend the truth and to defeat the lies.” In the Senate chamber on Saturday, 57 senators voted to convict Trump. But a two-thirds majority in the 100-member body was needed for the former president to be formally punished and stopped from running for office again. Seven Republican defections, among them Mitt Romney of Utah, the 2012 nominee for president, made it the most bipartisan impeachment verdict of four in US history. Every impeachment of a president has ended in acquittal: Andrew Johnson in 1868, Bill Clinton in 1999 and Trump in his first trial last year. But the final vote tally on Saturday also showed that 43 Republican senators were content to suggest inciting a mob to attack Congress and attempt to overturn an election did not merit punishment. Many, including minority leader Mitch McConnell, who excoriated Trump in a speech after the vote, said the trial was unconstitutional because Trump had left office. Experts disagreed and the Senate twice voted that hearings should proceed. Constitutional experts expressed concern for America’s 233-year-old system of government. Andrew Rudalevige of Bowdoin College told Axios: “Congress not even pushing back against a physical assault suggests that there’s a lot they will put up with.” Doug Jones, a former Democratic senator from Alabama, wrote: “In any trial, the accusing party must connect the dots between the words and actions of the defendant to the harm that occurred … the House managers did just that. “…If Trump’s actions are not impeachable, then nothing is, and we may as well strike that provision from the constitution.” While Trump was in office, Johnson cleaved so close to the president and his populist policies and style that Biden was reported to have called the prime minister “the physical and emotional clone of Donald Trump”. Asked on Sunday if he was concerned he and the new president might “start off on the wrong foot”, Johnson avoided the question. “I’ve had,” he said, “I think, already two long and very good conversations with the president and we had a really good exchange, particularly about climate change and what he wants to do.” Johnson also said the UK was “delighted now, I’m very delighted, to have a good relationship with the White House, which is an important part of any UK prime minister’s mission.” Such subjects, Johnson said, included Nato and Iran, “but above all, on the ways that the US and the UK are going to work together to deal with the environmental challenge that faces our planet. “And there, I think some of the stuff we’re now hearing from the new American administration and from the new White House is incredibly encouraging. And we want to work with the president on that.” Johnson will host a virtual meeting with Biden on 19 February, to discuss attempts to tackle the Covid-19 pandemic. According to Johns Hopkins University in Maryland, the US has recorded the most cases (27.5m) and most deaths (484,000) from the virus. The UK is in fourth place for cases (4m) and fifth for deaths (117,000), also behind India, Brazil and Mexico. The UK has a much higher figure for deaths per capita. Both the British and US governments have been pilloried for their attempts to tackle the problem. Touting vaccination efforts in the UK, Johnson told CBS: “I reckon science, in this arm wrestle, science is winning.”