The Obama administration and its support for democratic change in the Middle East has been on a collision course with Saudi Arabia, the United Arab Emirates and other traditional monarchies of the Persian Gulf. The crunch finally came this week with a sharp break over how to deal with protests in Bahrain.

The stakes in this latest crisis are high, even by Middle East standards, for it contains all the region’s volatile ingredients: tension between Saudis and Iranians, between Sunni Muslims and Shiites, and between democratic reformers and status-quo powers. Underlying this combustible mixture is the world’s most important strategic commodity, Persian Gulf oil. How’s that for a witch’s brew?

U.S. officials have been arguing that Bahrain’s Sunni monarchy must make political compromises to give more power to the Shiite majority there. The most emphatic statement came last weekend from Defense Secretary Bob Gates, who said during a visit to Bahrain that its “baby steps” toward reform weren’t enough and that the kingdom should step up its negotiations with the opposition.

This American enthusiasm for change has been anathema to the conservative regimes of the Gulf, and on Monday they backed Bahrain’s ruling Khalifa family with military force, marching about 2,000 troops up the causeway that links Bahrain to Saudi Arabia. A senior Saudi official told me the intervention was needed to protect Bahrain’s financial district and other key facilities from violent demonstrations. He warned that radical, Iranian-backed leaders were becoming more active in the protests.

“We don’t want Iran 14 miles off our coast, and that’s not going to happen,” said the Saudi official. U.S. officials counter that Iran, so far, has been only a minor player in the Bahrain protests and that Saudi military intervention could backfire by strengthening Iran’s hand.

“There is a serious breach” between the Gulf countries and Washington over the issue, warned a second Saudi official. “We’re not going in [to Bahrain] to shoot people, we’re going in to keep a system in place,” he said.

The Bahrain issue is the most important U.S.-Saudi disagreement in decades, and it could signal a fundamental change in policy. The Obama administration, in effect, is altering America’s long-standing commitment to the status quo in the Gulf, believing that change in Bahrain — as in Egypt, Tunisia and Libya — is inevitable and desirable.

The split reflects fundamental differences in strategic outlook. The Gulf regimes have come to mistrust Obama, seeing him as a weak president who will sacrifice traditional allies in his eagerness to be “on the right side of history.” They liken Obama’s rejection of Hosni Mubarak in Egypt to Jimmy Carter’s 1979 abandonment of the shah of Iran.

The crackup was predicted by a top UAE sheik in a February meeting with two visiting former U.S. officials. According to notes made during the conversation, the UAE official said: “We and the Saudis will not accept a Shiite government in Bahrain. And if your president says to the Khalifas what he said to Mubarak [to leave office], it will cause a break in our relationship with the U.S.” The UAE official warned that Gulf nations were “looking East” — to China, India and Turkey — for alternative security assistance.

The Obama White House hasn’t yielded to such pleas and threats from the Gulf. U.S. officials believe the Saudis and others have no good option to the United States as a guarantor of security. They note that military and intelligence contacts are continuing, despite the sharp disagreement over Bahrain.

In the end, this is a classic liberal-conservative argument about how best to achieve stability. The White House believes that security crackdowns won’t work any better in Bahrain than they did in Egypt or Tunisia — and that it’s time to embrace a process of democratic transition across the region. The Gulf monarchies and sheikdoms counter that concessions will only empower more radicalism — and that the big beneficiaries, in the end, will be Islamic radicals in Iran and al-Qaeda.

The trick is finding a formula for transition that doesn’t destabilize the Gulf and the global economy. White House officials talk as if this is an evolutionary process, but they should know better: As they saw in Egypt, change comes as a sudden shock — a nonlinear event that, in the case of the Gulf, will affect global energy and financial markets. Obama’s goal should be “progressive pragmatism,” with an emphasis on both those words.