Anti-American violence erupted across the Muslim world for a third day, with enraged protesters scaling the walls of U.S. embassies in Sudan and Tunisia and hard-pressed police waging street battles with demonstrators in several Middle East capitals.
Protesters tore down the flag at the U.S. Embassy in Tunis, the Tunisian capital, and set a nearby American school afire. In Khartoum, Sudan's capital, demonstrators breached an embassy wall and raised a black flag of militant Islam as police struggled to push them back. They also set fire to a building at the German Embassy compound.
At least four protesters were reported killed - two in Tunisia, one in Yemen and one in the Libyan capital, Tripoli - during attacks on American fast-food franchises Hardee's and KFC.
Triggered in large part by an amateurish video clip portraying the prophet Muhammad as a womanizer and child molester, the protests have strained U.S. relations with Egypt and raised tension in Libya, where an armed attack on the U.S. Consulate in Benghazi on Tuesday killed Ambassador J. Christopher Stevens and three other Americans.
At Andrews Air Force Base near Washington, U.S. President Barack Obama and Secretary of State Hillary Clinton attended a ceremony as the bodies of the four killed in Libya arrived home.
"The United States of America will never retreat from the world," Obama told the gathering. "We will never stop working for the dignity and freedom that every person deserves, whatever their creed, whatever their faith. That's the spirit that sets us apart from other nations."
At the ceremony, Clinton issued a veiled but steely warning to foreign leaders who fail to protect U.S. missions. "We've seen rage and violence directed at American embassies over an awful Internet video that we had nothing to do with," she said. "It is hard for the American people to make sense of that.
"Reasonable people and responsible leaders in these countries need to do everything they can to restore security and hold accountable those behind these violent acts," she said.
The protests were a reminder of the passions unleashed by the "Arab Spring," which toppled authoritarian regimes across the region, the unfulfilled longings of millions for a better life and the weaknesses of new governments still trying to find their footing. New leaders such as Egyptian President Mohamed Morsi find themselves in a bind.
Morsi and the Muslim Brotherhood were caught flatfooted when their rivals in the ultraconservative Salafist movement called for protests outside the U.S. Embassy on Tuesday. The Brotherhood wants to maintain its legitimacy on the streets, but it also needs to court international support and investment.
"For the Muslim Brotherhood, there is always this sense of trying to protect their right flank and to not cede ground to the Salafists," said Michael Wahid Hanna, a New York-based expert on Egypt.
U.S. State Department officials said Friday that security services in some countries responded sluggishly and had to be pushed to step up protection of U.S. sites.
The U.S. has sent Marine guards to shore up security at its missions in Libya and Yemen.
From Indonesia and Malaysia to Afghanistan and Pakistan, other demonstrators mounted less violent protests after Friday prayers. And in East Jerusalem, about 400 protesters trying to reach the U.S. Consulate threw stones and bottles at Israeli police, who held off the assault and arrested four people.
