Watching Saudi Arabia and other wealthy Gulf states line up behind the bloody counterrevolution in Egypt, you can’t help suspecting that these conservative monarchies are ready to fight to the last Egyptian against the Muslim Brotherhood — waging what amounts to a proxy war against the regional threat of Islamist extremism.

The events of the past few weeks have been the culmination of a trend building since February 2011, when President Hosni Mubarak was pushed from power in what many influential Saudis saw as U.S. abandonment of a traditional ally. Ever since, the Saudis and other Gulf states have been arguing, publicly and privately, that U.S. power is waning and that they must take more responsibility for their own security.

Leaders in Saudi Arabia, the United Arab Emirates and Bahrain have been disappointed that the United States hasn’t joined them in embracing the military government in Egypt that toppled President Mohamed Morsi. They see this as further evidence of American power in retreat globally, rather than, in simpler (and more accurate) terms, a function of the American public’s wariness, after Iraq and Afghanistan, of intervening in Muslim domestic conflicts.

This we-don’t-need-America tone was especially clear in a comment the other day by Prince Saud al-Faisal, the Saudi foreign minister, during a visit to France: “Concerning those who announced stopping their assistance to Egypt or threatening to stop them, the Arab and Islamic nation is rich with its people and capabilities and will provide a helping hand to Egypt.”

What’s troubling about Gulf support for the Egyptian generals and their crackdown is that it repeats one of the dominant themes of modern Arab political life: the meddling of the Saudis and fellow conservative states in other Arab conflicts partly to keep turmoil outside their borders. It’s what the divide-and-conquer British used to describe as a “forward” strategy.

The list of Saudi interventions is long: With the Kuwaitis and others, they bankrolled the Palestine Liberation Organization in Lebanon to the point of fomenting against the Christian-led government a civil war that raged for 15 years. They financed Saddam Hussein’s eight-year war against Iran; then, when an overconfident Hussein invaded Kuwait in 1990, they pleaded for a U.S. invasion to drive him back. After U.S. forces invaded once more in 2003 to overthrow Hussein, the Saudis backed Sunni groups in Iraq.

Then there were the Saudi-backed proxy wars against the old Soviet Union, most notably in Afghanistan. The Saudis (with strong U.S. support) encouraged Muslim insurgents, including the Afghan mujahideen groups that morphed into al-Qaeda and the Taliban. Washington has been struggling with the consequences of those covert actions since Sept. 11, 2001.

Saudi Arabia today deeply fears Iran, whose Shiite Muslim religion and Persian culture make it a traditional regional rival. The Saudis back Sunni forces in Lebanon against Iran’s proxy, Hezbollah; they back Sunni forces in Iraq who are waging an increasingly violent insurgency against the Shiite Prime Minister Nouri al-Maliki.

Then there’s Syria: Saudi Arabia is a leading supporter of Syrian rebels against President Bashar al-Assad. The Saudis dislike Assad for many reasons, but principally because he’s an Iranian proxy. Sometimes the Saudis work with the United States and Jordan to help the moderate rebel leader Gen. Salim Idriss. Other times, they allow money to flow to more extreme jihadist forces.

Complicating this regional, internecine rivalry is Saudi animosity toward Qatar and Turkey, which back the Muslim Brotherhood across the region and provided Morsi with financial and political support. These quarrels may seem at times to be petty and myopic, but they have devastating consequences.

The core problem for Saudi Arabia and the other Gulf regimes is that they have immense wealth resting uneasily on conservative political systems. They resist change, even as their young populations get ever more connected electronically with the outside world — and its online trends of both secularization and radical jihad. The U.A.E. has tried, with some success, to rebrand itself as a “moderate” force for modernization. A similar effort in Bahrain blew up in 2011 when the Saudis backed the conservative monarchy in a violent move against parties representing the Shiite majority.

The Saudis and the Emiratis must decide how best to protect their own security and stability. The United States shouldn’t assume that Gulf countries’ interests and its own coincide. The idea that a Saudi-backed crackdown in Egypt that drives the Muslim Brotherhood underground will protect the conservative monarchies seems short-sighted, to put it mildly. But it’s their money.

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