Tensions over the Iran war have rocked the so-called 'special relationship' ahead of a trip that was meant to mark the United States' 250th anniversary of independence from the British monarch's ancestors.

The state visit to the US looks fraught with difficulty - but could be key to rescuing the special relationship.

The White House revealed new details for King Charles’ upcoming U.S. visit. Find out what’s planned during the four-day royal trip.