Secretary of State Hillary Rodham Clinton said Tuesday that the Arab world's revolutions could be remembered as "just a mirage in the desert" if leaders fail to make good on demands for greater democracy and economic opportunity.

The warning from the Obama administration's top diplomat came amid increased signs of a backslide in the so-called Arab Spring, as Moammar Gadhafi persists with a bloody war against Libyan rebels and leaders from Yemen to Syria to Bahrain violently resist the calls from their people for a democratic transformation. Even in Egypt and Tunisia, where revolutions successfully chased out presidents who ruled for a combined 54 years, reform processes are at risk.

Speaking at the annual U.S.-Islamic World Forum, Clinton said this was the first real chance in decades for fundamental change in the region.

"Will the people and leaders of the Middle East and North Africa pursue a new, more inclusive approach to solving the region's persistent political, economic and social challenges?" Clinton asked. "Will they consolidate the progress of recent weeks and address long-denied aspirations for dignity and opportunity? Or, when we meet at this forum in one year or five years or 10, will we have seen the prospects for reform fade and remember this moment as just a mirage in the desert?"

The speech was in many ways a sequel to one she gave in Doha, Qatar, in January, when she warned Arab governments that they risked "sinking into the sand" if they did not meet the needs of their people. A day later, Tunisian President Zine El Abidine Ben Ali fled his country amid mass protests demanding his ouster. Egypt's Hosni Mubarak stepped down under similar pressure a month later.

Clinton didn't answer the fundamental question she posed: Will the unrest that has spread across the Arab world produce truly free societies with economic opportunities for their people, or leave corrupt and repressive systems in place?

She stressed that much has already been accomplished, with protest movements shattering the myth that Arabs don't share the same aspirations for freedom, dignity and opportunity, or that change could only come through violence. The use of Facebook, Twitter and other social media networks has helped mobilize younger citizens, who are increasingly connected, organized and frustrated — and unwilling to be silenced by tanks and missiles.

"Changing leaders alone will not be enough to satisfy them," Clinton said.

She said real change in Egypt and Tunisia demands political parties and civil society campaigns, and the protesters who brought down their governments need to combine their passion with the practical work of politics. At the same time, she said, transitional authorities must be inclusive, respect rights such as free assembly and provide basic security on the streets. Corruption needs to be rooted out, martial law eliminated, independent judicial systems established and fair elections held, she said.

Clinton spoke as the administration criticized Egypt's military council after a tribunal convicted 26-year-old blogger Maikel Nabil Sanad of insulting the army and sentenced him to three years in prison, the latest sign that the army may be reversing the reform process. Sanad carried reports of abuses by the military and accused it of remaining loyal to ousted President Hosni Mubarak.

"This is not the kind of progress we're looking for," State Department spokesman Mark Toner said.

Clinton also lamented the continued plight of women in Egypt and Tunisia, where they've been excluded from transitional processes. When women marched through the site of the Cairo revolution, Tahrir Square, to celebrate International Women's Day, they were met by harassment and abuse, she noted.

"You cannot have a claim to a democracy if half the population is silenced," Clinton said. "People have the right and responsibility to devise their own government. But there are universal rights that apply to everyone and universal values that undergird vibrant democracies everywhere."

Clinton said the U.S. has made clear that security alone cannot resolve the crisis in Bahrain, where the Sunni monarchy has suppressed Shiite protesters with the help of Saudi Arabia and other neighbors.

In Yemen, Clinton stopped short of calling for President Ali Abdullah Saleh to step down after 33 years in power but called for "meaningful political change ... in an orderly and peaceful manner."

And she condemned the "abhorrent" violence by Syria's government against protesters she said were right to demand more freedom from President Bashar Assad.

"All the signs of progress we have seen in recent months will only be meaningful if more leaders in more places move faster and further to embrace this spirit of reform," Clinton said, evoking the memory of Iran's 1979 revolution which was "subverted by a new and brutal dictatorship" and warning that Iranian leaders and al-Qaida propagandists are trying to yoke the Arab world's peaceful protests for their own ends.

Governments need to diversify their economies, open their political systems, fight corruption and ensure the rights of women and minorities, she said. "Those are the questions that will determine whether the people of the region make the most of this historic moment or fall back into stagnation."