President Hosni Mubarak's decision to step down Friday after three decades in power presents the Obama administration with a political vacuum where a stalwart ally once stood, shaking up the Arab Middle East in ways that present as much peril as promise for U.S. interests in the region.
Emerging from the secular nationalist movement that produced Gamal Abdel Nasser and Anwar Sadat, Mubarak presented five U.S. presidents with a choice: push for greater democracy in a bellwether nation that gave birth to modern political Islam or tolerate repression in the name of regional stability and to support an Arab government willing to offer Israel a tepid partnership.
For decades, the U.S. government chose the latter path. But the option came at the expense of U.S. popularity among Egyptians and the millions of other Arabs living under U.S.-backed autocrats in Tunisia, Jordan, Saudi Arabia, Yemen and the Gulf emirates.
President Barack Obama sought to soften that legacy during the weeks of demonstrations in Cairo by calling for a swift political transition from Mubarak's rule to fair elections, irking U.S. allies among the region's other autocrats but failing to appease the Egyptians in the streets.
In a brief statement on Mubarak's resignation, Obama said Friday that the United States would remain a "friend and partner" during the country's tumultuous political transition, which he called on Egypt's military to make sure "is credible in the eyes of the Egyptian people."
"This is not the end of Egypt's transition," Obama said. "It is the beginning."
The American record of support for Mubarak will likely shape the democratic process that may emerge from the protests of Tahrir Square and the posture of such opposition groups as the Muslim Brotherhood. The wellspring of the region's Islamist political movements, its opposition to Israel endures.
Mubarak leaves behind the rigid institutions and laws of a police state, including the emergency decree he used to suspend many civil liberties, and a powerful army with a large stake in who leads the country. Egypt's Armed Forces Supreme Council announced Friday it would rule the country, at least temporarily.
"Obama's insistence that this was about how Egypt is governed, not who governs Egypt, which was awkward for him, is actually the right thing to be insisting on now that Mubarak is gone," said Tom Malinowski, the Washington director of Human Rights Watch.
"A successful transition would have implications in and beyond the Arab world," he continued. "It will be inspiring for opposition movements, but also potentially something that causes governments to crack down harder."
By necessity, the Obama administration is already looking beyond Cairo, just as it quickly turned the page on Tunis after President Zine Abidine Ben Ali fled amid public protest last month, to the monarchies of Saudi Arabia and Jordan, the only other Arab nation at peace with Israel.
What senior U.S. officials see in those kingdoms' economic stagnation, youthful populations, and simmering political frustration is a potential echo of Tunis and Cairo — and political change that could usher out allies in favor of an angry, anti-Western opposition. How to encourage the election of governments not only responsive to their electorates but also to U.S. interests remains the uncharted challenge ahead.
"There are a number of countries in the Arab world that reflect some of the same concerns … the lack of freedoms, the lack of political reform, the lack of truly free and open elections," CIA director Leon Panetta told the House Intelligence Committee this week. "The triggers, the factors that kicked off what happened in Egypt could very well impact in other areas."