US Secretary of State Rex Tillerson told reporters in Doha that the Qatari government had "reasonable" views in the month-old diplomatic  crisis with Arab neighbours. "I think Qatar has been quite clear in its positions, and I think those have been very reasonable," Tillerson said after his arrival in Doha on Tuesday. The quartet accuse Qatar of funding "terrorism", an accusation Qatar rejects as "baseless".

Not long before a major crisis ripped through the Middle East, pitting the United States and a bloc of Gulf countries against Qatar, Jared Kushner’s real estate company had unsuccessfully sought a critical half-billion dollar investment from one of the richest and most influential men in the tiny nation, according to three well-placed sources with knowledge of the near transaction. Qatar is facing an ongoing blockade led by Saudi Arabia and the United Arab Emirates, and joined by Egypt and Bahrain, which President Trump has taken credit for sparking. Kushner, meanwhile, has reportedly played a key behind-the-scenes role in hardening the U.S. posture toward the embattled nation.

The head of Iran’s atomic energy organisation, one of the architects of the 2015 landmark nuclear deal, has warned the US to stop upsetting the regional balance of power by siding with Saudi Arabia. Writing in the Guardian, Ali Akbar Salehi said “lavish arms purchases” by regional actors – a reference to the Saudi purchase of $100bn of US arms during Donald Trump’s recent visit to Riyadh – would be seen as provocative in Tehran and that it would be unrealistic to expect Iran to remain “indifferent”.

President Trump has done business with royals from Saudi Arabia for at least 20 years, since he sold the Plaza Hotel to a partnership formed by a Saudi prince. Mr. Trump has earned millions of dollars from the United Arab Emirates for putting his name on a golf course, with a second soon to open. He has never entered the booming market in neighboring Qatar, however, despite years of trying.

While President Trump berates Qatar for sponsoring terrorism at the highest levels, he is simultaneously authorizing the country to purchase over $21 billion of U.S. weapons.  One portion of that deal -- $12 billion for 36 F-15QA fighter jets -- was inked on Wednesday in Washington, D.C., when Qatar's Defense Minister met with U.S. Defense Secretary James Mattis.

Escalating a feud among Persian Gulf monarchs, Saudi Arabia and the United Arab Emirates on Friday listed 59 people and a dozen organizations said to have links to Qatar, including prominent Qatari businessmen, politicians and royalty, as aiding terrorism. Germany’s foreign minister, Sigmar Gabriel, had previously attributed the escalation of the dispute to what he called a dangerous “Trumpification” of regional politics.