Ras al-Khaimah is a strategic western ally that sits on the Straits of Hormuz, the world's most important seaway, and is just 60 miles across the water from Iran. Sheikh Khalid al-Qasimi, the elder son of the late ruler, Sheikh Saqr bin Mohammed al-Qasimi, was on Wednesday night holed up in his palace, claiming to be the rightful successor, while troops were marshalled outside to enforce the claim of his younger brother, the Crown Prince Sheikh Saud.
Sheikh Khalid accuses Sheikh Saud, who deposed him as Crown Prince and de facto ruler in 2003, of allowing the emirate to be used as a route to smuggle banned goods, including nuclear technology, into Iran, and is appealing to his family to put him in charge.
But the federal authorities of the United Arab Emirates, of which Ras al-Khaimah is part, immediately pledged their "full support" to Sheikh Saud yesterday morning. Within hours, Sheikh Khalid's palace was surrounded by military vehicles.
Were it not for its closeness to Iran, the long struggle for power between the two brothers would seem like something from the writings of Lawrence of Arabia rather than a means of organising government in a fast-modernising nation. But 20 per cent of the world's oil supplies pass through the Straits of Hormuz and the monarch's death comes as Iran is stepping up its influence across the Middle East.
Abu Dhabi, which dominates the UAE politically and economically thanks to its huge oil reserves, has been attempting to reduce Iranian influence in both Dubai and Ras al-Khaimah, the two emirates with the strongest ties. But it has had to counter long trading links and a history of self-government by smaller neighbours. Analysts say Sheikh Saud seems assured of the succession thanks to federal support, but any prolonged dispute would be viewed as a severe threat by western allies including Britain.
Senior Gulf leaders were thought to be trying to negotiate a peaceful departure for Sheikh Khalid, but sources indicated he might have to be "made to leave one way or another" if he did not go quietly.
Sheikh Khalid was Crown Prince for much of the reign of his father, who came to power in 1948 and at his death at the age of 92 was the last remaining of the seven local rulers who founded the UAE in the early 1970s.
After he was deposed he went into exile and mounted a sometimes eccentric campaign to regain his position from New York and London.
He hired a British lawyer, Peter Cathcart, usually a family solicitor based in Uxbridge; a Californian public relations firm; and a Washington lobbyist to press his case.
Key to his argument was a claim that his brother was developing close relations with Iran, allowing his emirate to be used as a smuggling route.
The UAE has always denied these claims, but when Sheikh Khalid was allowed to enter the country to visit his father in an Abu Dhabi hospital, and then to take up residence in the emirate of Sharjah, there was speculation he was winning the public relations battle.
