Washington/London, April 30 -- King Charles III called on the US to maintain its leadership role in the world, and to support Ukraine and the North Atlantic Treaty Organisation, in a remarkably pointed speech for a monarch that urged Americans to resist the pull of isolationism. Charles used his remarks to a joint session of Congress - the first such address by a British monarch in more than three decades - to argue for preserving the alliance between the UK and US. The king appealed to the shared heritage between the two nations, littering his remarks with references to culture, religion and principles behind America's decision to declare independence 250 years ago. "I pray with all my heart that our alliance will continue to defend our shared values, with our partners in Europe and the Commonwealth, and across the world, and that we ignore the clarion calls to become ever more inward-looking," Charles told the assembled lawmakers, with Vice President JD Vance and House Speaker Mike Johnson seated behind him. The relationship between the US and the UK has fallen to its lowest level in decades amid a messy public feud between President Donald Trump and Prime Minister Keir Starmer. Trump has spent recent months criticizing and insulting Starmer - with whom he previously shared a warm relationship - before Starmer split with the president over the war in Iran and his threats about annexing Greenland. The speech on Capitol Hill came on the second day of his four-day state visit, a trip that has thrust Charles into an unusually prominent diplomatic role. While his words were carefully measured, the king's message at several points - including on supporting Nato and Ukraine, as well as calls for environmental stewardship - could be read as an implicit critique of the Trump administration's policies. The king's remarks - during which he was repeatedly interrupted by applause - stressed the durability of a relationship that began with a revolution. "With the spirit of 1776 in our minds, we can perhaps agree that we do not always agree - at least in the first instance," Charles said. Trump, who has made little secret of his admiration of royalty in general and the British monarchy in particular, was due to host Charles at a state banquet after the speech. Earlier, the president had praised the king before a meeting at the White House, hailing the "cherished" bond between two nations. "In the centuries since we won our independence, Americans have had no closer friends than the British," Trump said. The president called Charles a "blessing" to the countries' relationship and predicted, "I am very certain that it will continue that way long into the future." Charles attended a greeting ceremony hosted by Trump on the South Lawn of the White House, which featured an honour guard, military band, ceremonial cannon salute and a flyover. Trump at times veered from his script to praise Charles, recalling how his Scottish-born mother watched the royal as a young man during televised ceremonies. "My mother had a crush on Charles," the president said. The king's remarks to Congress, however, were more pointed, coming amid growing international concern about the US's commitment to the post-war order it had helped build. Charles mentioned how the United Nations and Nato had come to America's defence in the wake of the September 11 terror attacks and cited the UK's "shoulder-to-shoulder" cooperation with the US through two world wars. He argued that the partnership between Europe and America was "more important today than it has ever been," he said. He said that "unyielding resolve is needed for the defense of Ukraine and her most courageous people - in order to secure a truly just and lasting peace," echoing his remarks to Trump in September. Even the king's nods to history could be received by an American audience as veiled warnings, intentional or not. Charles cited the example of Britain's Magna Carta as giving the US inspiration on how executive authority should be subject to checks and balances. His comment comes amid criticism that the Republican-held Senate and House have too widely deferred to Trump's sweeping expansion of executive power. Democratic leaders could be seen in the chamber standing and applauding the line. Similarly, his exhortation about the need for an independent judiciary stands in contrast to the president's frequent criticisms of judges and Supreme Court justices who rule against his own wishes. While Charles didn't reference Iran specifically, he cited "times of conflict from Europe to the Middle East," which he warned poses "immense challenges for the international community and whose impact is felt in communities the length and breadth of our own countries." Europe is currently grappling with an energy price shock as well as a looming jet fuel crisis that threatens summer air travel. Though Republicans at times displayed muted responses - to Charles' calls on the importance to protect the environment for example - there was overwhelming support for the king with several standing ovations throughout the speech. Republican Whip Tom Emmer said Charles "was well measured and respectful which was nice." Representative Robert Aderholt said the call to support Ukraine was received well....