LONDON, April 24, 2026 (BSS/AFP) - King Charles III heads to the United States on Monday with transatlantic tensions over the Iran war and the Epstein scandal's long shadow threatening to intrude on the landmark visit.

Both Buckingham Palace and the British government have said the four-day trip will honour the historic relationship between the two countries as the US marks 250 years of independence. 

Charles's first US state visit as monarch comes at the request of the UK government and President Donald Trump and will be made with Queen Camilla, according to the palace.

However, as the American leader's war with Iran drives a rare wedge between London and Washington, it has generated considerable controversy.

Trump has repeatedly lambasted British Prime Minister Keir Starmer over his war opposition, alongside his government's immigration and energy policies.

"This is not Winston Churchill that we're dealing with," Trump grumbled in March, adding the so-called special relationship was "not like it used to be". The American leader has also mocked the perceived state of Britain's armed forces -- of which the king is commander-in-chief.

In turn, Starmer has stepped up his public criticism of the war, while stressing the breadth and depth of UK-US ties in defending the state visit. An early April YouGov poll found 48 percent of Britons support cancelling it.

"Often what the monarchy is able to do, through the bonds that they build, is reach through the decades in a situation like this," Starmer told MPs when asked why the trip was going ahead.

Trump -- a vocal admirer of the royals whose mother was Scottish -- told the BBC on Thursday the visit could "absolutely" help repair relations, praising the king as "fantastic".

- 'Politics' -

Charles, 77, showcased his diplomatic skills during Trump's state visit to Britain last September, with Royal Holloway University of London monarchy expert Craig Prescott noting he is "generally very good" at navigating such occasions.

Prescott said the independence anniversary provided a useful "get out" for the British side to argue the trip is "not about Keir Starmer and Donald Trump, per se".

But he acknowledged it was "that little bit closer to politics" than usual and Charles would likely address the "very big elephant in the room" in a coded way in his speech Tuesday to the US Congress.

The first British monarch to address Congress since his mother, the late queen Elizabeth II, in 1991, he will mark the two countries' shared history and deep ties, the palace has said.

"He might refer to how the special relationship has perhaps waxed and waned over time," Prescott predicted, arguing Charles has proven to be a "better speaker" than his mother.

But Graham Smith, of the anti-monarchy campaign group Republic, argued the king will "go through the rituals without offering anything of substance".

The only critical thing "about this pointless trip is how Trump behaves," he said on X.

Meanwhile, the scandal around late US sex offender Jeffrey Epstein threatens to encroach on the highly choreographed tour.

Charles has faced a major crisis over the friendship his brother Andrew Mountbatten-Windsor, previously known as prince Andrew, had with the late billionaire, who died in prison in 2019.

The longstanding controversy intensified after Andrew was arrested in mid-February following new revelations over their links.