King Charles III will visit the US in late April, Buckingham Palace announced Tuesday, despite some calls for the trip to be cancelled or delayed amid strains over the Iran war.Confirmation of the monarch's first state visit to the US comes at a rocky time for the so-called US-UK "special relationship", with US President Donald Trump repeatedly criticising Prime Minister Keir Starmer's reticence over the US-Israel war against Tehran.But Trump, whose mother came from Scotland and is a big fan of the British monarchy, welcomed news of the visit as "TERRIFIC".The US leader posted on his Truth Social platform that the trip would take place on April 27-30 and include a "beautiful Banquet Dinner at the White House on the evening of April 28th"."I look forward to spending time with the King, whom I greatly respect. It will be TERRIFIC!" he added.The visit will come as the US marks its 250th anniversary of independence and will be followed by an official visit by the king to Bermuda, a British Overseas Territory.Washington's envoy to Britain, Warren Stephens, warned last week it would be a "big mistake" for the US visit to be cancelled.Trump has repeatedly railed against Starmer since the start of the war, accusing him of not doing enough to support the US."This is not Winston Churchill that we're dealing with," Trump said earlier this month, after Starmer initially declined to let US warplanes fly from UK bases to strike Iran."I'm disappointed with Keir," Trump has also said, slamming Starmer's "big mistake".Trump also caused offence with recent remarks about UK troops' participation in Afghanistan.The visit will be Charles's first trip to the US as king, after he hosted Trump for a lavish state visit last September.The mercurial US president has frequently expressed admiration for Britain's royal family, which treated him to a full state dinner at Windsor Castle, military parades and a flyover during last year's visit.— Soft power diplomacy —It was an unprecedented second state visit for Trump, who was also hosted in 2019 by the late queen Elizabeth II before her death.But in his latest broadside aimed at Starmer's government, Trump told countries like Britain to secure the Strait of Hormuz themselves because "the USA won't be there to help you anymore, just like you weren't there for us".A YouGov poll published on Thursday found nearly half of British citizens opposed the king's visit to the US, with only a third saying it should go ahead.Emily Thornberry, a senior MP in Starmer's ruling Labour party, said earlier this month it would be "safer to delay" the trip.She warned Charles and Camilla could be left feeling "embarrassed" because of the ongoing conflict."Why are we rewarding Donald Trump with a state visit from our king?" asked Ed Davey, leader of the minority opposition Liberal Democrats party.The last British monarch to make a state visit to the US was Queen Elizabeth II in 2007.That visit was the last of four made by the late queen whose visit in 1991 included an address to Congress.The royal family's soft power diplomacy is viewed as an important way of engaging with Trump.Charles helped smooth Starmer's visit to the White House last year by signing a letter inviting Trump to visit the UK which the prime minister handed to the president in the Oval Office.In front of the TV cameras a beaming US president read the invitation and declared the king "a beautiful man, a wonderful man".