Charles will also become the first British monarch to address Congress since his mother, the late Queen Elizabeth II, in 1991.The trip is intended to celebrate the historic ties between the two countries ahead of the 250th anniversary of US independence, with White House press secretary Karoline Leavitt saying it would "honour the long-standing and special relationship".But it comes at a time of considerable strain in that relationship, as Trump continues his war in Iran and criticises allies who have declined to step in.In recent weeks, Trump has criticised UK Prime Minister Keir Starmer over his unwillingness to join US military attacks on Iran, dismissing him as "not Winston Churchill" — referring to the World War Two-era prime minister who coined the "special relationship" name for the UK-US bond "His mother really went out of her way to avoid political machinations or participating in them [publicly]," Mondschein said."I think King Charles, in this instance, will probably continue, formally at least, to avoid political engagement and focus more on the cultural and historic ties between the United States and in the United Kingdom."But behind closed doors, he said, the king may be working more pointedly to stabilise the relationship and underscore the value of the alliance.— With additional reporting by Agence France-Presse and Associated Press.For the latest from SBS News, download our app and subscribe to our newsletter.