Qatar is unexpectedly under siege from its neighbours. Led by Saudi Arabia and the United Arab Emirates, supported by Egypt, Bahrain and Yemen, the five Arab states have cut diplomatic relations with Qatar, severed land, air and sea travel and are expelling Qatari citizens who have 48 hours to depart.

The Saudis and their allies are demanding, in effect, that Qatar end its independent foreign policy and tame or close down its television station, Al Jazeera. They claim that Qatar is complicit with Iran in supporting terrorism, though Qatar is one of the loose coalition of Sunni states supporting forces hostile to Iran in Syria and Yemen.

One pro-Saudi lobbyist in the US even threatens regime change in Qatar, tweeting to its Emir: “I would like to remind you that [elected Egyptian President] Mohammed Morsi did exactly the same [as you] and was then toppled and imprisoned.”

Saudi Arabia and Qatar have long been rivals and, despite Qatar’s small size, its great wealth and vast gas reserves have given it great influence. It backed the Arab Spring with its wealth and media outlets, supporting the Muslim Brotherhood in Egypt and Hamas in Gaza.

Saudi Arabia cuts ties with Qatar over terror links

Three years ago in 2014 there was a similar but less serious confrontation between Qatar and its neighbours, who accused it of interference in their internal affairs. Since then Qatar has been much more compliant in not confronting or pursuing radically different policies from those of Saudi Arabia and the UAE.

What has changed in the Gulf to precipitate a crisis now? The answer is that the Trump wrecking ball passed through the region last month and the US President’s unreserved backing for Saudi Arabia, and in particularly for deputy Crown Prince Mohammed bin Salman, has disturbed the regional balance of forces. It has already emboldened the Sunni monarchy in Bahrain to crush the last Shia resistance to its dominance, killing five protesters in one village and closing down the only remaining independent newspaper.

Much more seriously, Mr Trump’s unqualified support for the Sunni monarchies and autocrats during his two-day visit to Riyadh emboldened the kingdom to start a second and, it hopes, final round in its confrontation with Qatar. Mr Trump may not have intended to touch off this latest crisis when he aggressively and inaccurately demonised Iran and by implication the Shia as the source of all terrorism in the Middle East and North Africa. But his words were interpreted by the Saudis as enabling them to move against Qatar though it is home to a major US base.

In pictures: President Donald Trump on tour Show all 39 1 /39 In pictures: President Donald Trump on tour In pictures: President Donald Trump on tour 20 May 2017 US President Donald Trump and Saudi Arabia's King Salman bin Abdulaziz al-Saud arriving for a reception ahead of a banquet at Murabba Palace in Riyadh Getty Images In pictures: President Donald Trump on tour 20 May 2017 US President Donald Trump, accompanied by First Lady Melania Trump, and Saudi Arabia's King Salman bin Abdulaziz al-Saud being welcomed at Murabba Palace in Riyadh Getty Images In pictures: President Donald Trump on tour 20 May 2017 US President Donald J. Trump with King of Saudi Arabia Salman bin Abdulaziz Al Saud during a welcome ceremony with traditional sword dancers at Murabba Palace, in Riyadh, Saudi Arabia EPA In pictures: President Donald Trump on tour 20 May 2017 King of Saudi Arabia Salman bin Abdulaziz Al Saud with US President Donald J. Trump and wife Melania during a welcome ceremony at Murabba Palace, in Riyadh, Saudi Arabia EPA In pictures: President Donald Trump on tour 20 May 2017 US President Donald Trump adjusts the Collar of Abdulaziz Al Saud Medal, after it was bestowed upon him by Saudi Arabia's King Salman bin Abdulaziz Al Saud at the Royal Court in Riyadh, Saudi Arabia Reuters In pictures: President Donald Trump on tour 20 May 2017 Saudi Arabia's King Salman bin Abdulaziz Al Saud presents U.S. President Donald Trump with the Collar of Abdulaziz Al Saud Medal at the Royal Court in Riyadh, Saudi Arabia Reuters In pictures: President Donald Trump on tour 21 May 2017 Palestinians print posters depicting US President Donald Trump in preparations for his planned visit, in the West Bank town of Bethlehem Reuters In pictures: President Donald Trump on tour 21 May 2017 US President Donald Trump accompanied by first lady Melania Trump, his daughter Ivanka Trump and her husband White House senior advisor Jared Kushner, before delivering his remarks to the Arab Islamic American Summit in Riyadh, Saudi Arabia Reuters In pictures: President Donald Trump on tour 21 May 2017 US President Donald Trump looks on as U.S. Secretary of State Rex Tillerson and Saudi Arabia's Crown Prince Muhammad bin Nayef exchange a memorandum of understanding Reuters In pictures: President Donald Trump on tour 21 May 2017 First Lady Melania Trump shares a laugh with a child during a visit to the American International School in the Saudi capital Riyadh Getty Images In pictures: President Donald Trump on tour 21 May 2017 US President Donald Trump holds a bilateral meeting with Bahrain's King Hamad bin Isa Al Khalifa AP In pictures: President Donald Trump on tour 22 May 2017 Israeli soldiers rest during preparations ahead of President Trump's landing in Tel Aviv, Israel Getty Images In pictures: President Donald Trump on tour 22 May 2017 First Lady Melania Trump makes her way to board Air Force One in Riyadh as she heads with her husband the US President to Israel Getty Images In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump and first lady Melania Trump board Air Force One for Israel, the next stop in Trump's international tour, at King Khalid International Airport AP In pictures: President Donald Trump on tour 22 May 2017 Israeli soldiers wait for the arrival ceremony of US President Donald Trump at Ben Gurion airport near Tel Aviv, Israel AP In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump and first lady Melania Trump arrive aboard Air Force One at Ben Gurion International Airport in Lod near Tel Aviv, Israel Reuters In pictures: President Donald Trump on tour 22 May 2017 US President Donald Trump and first lady Melania Trump disembark Air Force One on arrival at Ben Gurion International Airport AP In pictures: President Donald Trump on tour 22 May 2017 US President Donald J. 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Trump, touches the Western Wall, Judaism's holiest prayer site, in Jerusalem's Old City EPA In pictures: President Donald Trump on tour 22 May 2017 President Donald Trump visits the Western Wall AP In pictures: President Donald Trump on tour 24 May 2017 US President Donald J. 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