Qatar has in the past upset its Gulf neighbours. They are annoyed by its ownership of Al Jazeera, by far the region's most important TV network and critic of other Arab leaders. Its alleged sponsorship of various Islamist movements is another source of friction.
But the recent decision of Saudi Arabia, Egypt, the United Arab Emirates and Bahrain to break off diplomatic ties and impose an almost total blockade on Qatar represents a serious escalation of tensions.
Qatar blames its troubles on a misunderstanding caused, allegedly, by the spreading of fake news through the hacking of its national news agency's website. But in reality, the dispute between Qatar and Saudi Arabia, the Gulf's biggest power, has been brewing for years, and recently came to a head, due to two disparate developments.
The first is reportedly Qatar's decision to pay pro-Iranian militias in Iraq a big ransom to free some kidnapped Qatari citizens, a move said to have infuriated the Saudis, who are keen to limit Iran's influence.
And then there is Qatar's support for the Palestinian militant group, Hamas, and the Muslim Brotherhood, a pan-Arab organisation regarded as a menace by the Gulf monarchies.
Yet key to the Saudis' unusually tough response is US President Donald Trump's decision to swing behind them and anoint them as the Gulf's leaders. It emboldened Saudi King Salman to "discipline" his unruly neighbour.
Whenever such spats erupted in the past, the United States tried to mediate. Not this time. And that means Qatar will most likely give in.
But in many respects, this spat, however resolved, is a sideshow. It will not render the Gulf states more cohesive. Crucially, it does nothing to clarify how at a time of growing Sunni-Shi'ite conflict, Saudi Arabia and the Sunni states will deal with Iran's growing influence, which remains one of the region's biggest security challenges.
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