U.S. and Saudis in Growing Rift as Power Shifts Secretary of State John Kerry was escorted by the Saudi foreign minister, Prince Saud al-Faisal, as he arrived in Riyadh on Nov. 3. WASHINGTON - There was a time when Saudi and American interests in the Middle East seemed so aligned that the cigar-smoking former Saudi ambassador, Prince Bandar bin Sultan, was viewed as one of the most influential diplomats in Washington. Those days are over. The Saudi king and his envoys - like the Israelis - have spent weeks lobbying fruitlessly against the interim nuclear accord with Iran that was reached in Geneva on Sunday. In the end, there was little they could do: The Obama administration saw the nuclear talks in a fundamentally different light from the Saudis, who fear that any letup in the sanctions will come at the cost of a wider and more dangerous Iranian role in the Middle East. Although the Saudis remain close American allies, the nuclear accord is the culmination of a slow mutual disenchantment that began at the end of the Cold War. For decades, Washington depended on Saudi Arabia - a country of 30 million people but the Middle East's largest reserves of oil - to shore up stability in a region dominated by autocrats and hostile to another ally, Israel. The Saudis used their role as the dominant power in OPEC to help rein in Iraq and Iran, and they supported bases for the American military, anchoring American influence in the Middle East and beyond. But the Arab uprisings altered the balance of power across the Middle East, especially with the ouster of the Egyptian president, Hosni Mubarak, a close ally of both the Saudis and the Americans. The United States has also been reluctant to take sides in the worsening sectarian strife between Shiite and Sunni, in which the Saudis are firm partisans on the Sunni side. At the same time, new sources of oil have made the Saudis less essential. And the Obama administration's recent diplomatic initiatives on Syria and Iran have left the Saudis with a deep fear of abandonment. "We still share many of the same goals, but our priorities are increasingly different from the Saudis," said F. Gregory Gause III, a professor of Middle East studies at the University of Vermont. When you look at our differing views of the Arab Spring, on how to deal with Iran, on changing energy markets that make gulf oil less central - these things have altered the basis of U.S.-Saudi relations. The United States always had important differences with the Saudis, including on the Israeli-Palestinian conflict and the spread of fundamentalist strains of Islam, Mr. Gause added. But the Obama administration's determination to ease the long estrangement with Iran's theocratic leaders has touched an especially raw nerve: Saudi Arabia's deep-rooted hostility to its Shiite rival for leadership of the Islamic world. Saudi reaction to the Geneva agreement was guarded on Monday, with the official Saudi Press Agency declaring in a statement that "if there is good will, then this agreement could be an initial step" toward a comprehensive solution for Iran's nuclear ambitions. In recent days, Saudi officials and influential columnists have made clear that they fear the agreement will reward Iran with new legitimacy and a few billion dollars in sanctions relief at exactly the wrong time. Iran has been mounting a costly effort to support the government of the Syrian president, Bashar al-Assad, including arms, training and some of its most valuable Revolutionary Guards commandos, an effort that has helped Mr. Assad win important victories in recent months. The Saudis fear that further battlefield gains will translate into expanded Iranian hegemony across the region. Already, the Saudis have watched with alarm as Turkey - their ally in supporting the Syrian rebels - has begun making conciliatory gestures toward Iran, including an invitation by the Turkish president, Abdullah Gul, to his Iranian counterpart to pay an official visit earlier this month. In the wake of the accord's announcement on Sunday, Saudi Twitter users posted a wave of anxious, defeatist comments about being abandoned by the United States.