Egyptian demonstrators stand on a wall erected by security and hurl rocks at riot police in Tahrir Square on January 25, 2013. Huge crowds are expected to demonstrate in Egypt on the second anniversary of the revolution that ousted Hosni Mubarak and brought in an Islamist government, as political tensions simmer and economic woes bite. AFP PHOTO/MOHAMMED ABED (Photo credit should read MOHAMMED ABED/AFP/Getty Images)
Egyptian demonstrator wave the national flag and shout slogans during a protest in Tahrir Square on January 25, 2013. Huge crowds are expected to demonstrate in Egypt on the second anniversary of the revolution that ousted Hosni Mubarak and brought in an Islamist government, as political tensions simmer and economic woes bite. AFP PHOTO/MOHAMMED ABED (Photo credit should read MOHAMMED ABED/AFP/Getty Images)
Egyptian demonstrator hurls rocks at riot police during clashes in Tahrir Square on January 25, 2013. Huge crowds are expected to demonstrate in Egypt on the second anniversary of the revolution that ousted Hosni Mubarak and brought in an Islamist government, as political tensions simmer and economic woes bite. AFP PHOTO/MOHAMMED ABED (Photo credit should read MOHAMMED ABED/AFP/Getty Images)
An Egyptian demonstrator hurls rocks at riot police during clashes in Tahrir Square on January 25, 2013. Huge crowds are expected to demonstrate in Egypt on the second anniversary of the revolution that ousted Hosni Mubarak and brought in an Islamist government, as political tensions simmer and economic woes bite. AFP PHOTO/MOHAMMED ABED (Photo credit should read MOHAMMED ABED/AFP/Getty Images)
Egyptians treat a wounded protestor during clashes with riot police in Tahrir Square on January 25, 2013. Huge crowds are expected to demonstrate in Egypt on the second anniversary of the revolution that ousted Hosni Mubarak and brought in an Islamist government, as political tensions simmer and economic woes bite. AFP PHOTO/MOHAMMED ABED (Photo credit should read MOHAMMED ABED/AFP/Getty Images)
Egyptian protesters take part in a protest in Tahrir Square to call for the fall of Islamist President on January 24, 2012 in Cairo. Police clashed with protesters in Cairo earlier, on the eve of the the second anniversary of the uprising that overthrew Hosni Mubarak, as they tried to dismantle a security barrier and called for the fall of President Mohamed Morsi. AFP PHOTO/MOHAMMED ABED (Photo credit should read MOHAMMED ABED/AFP/Getty Images)
Egyptian protesters take part in a protest in Tahrir Square to call for the fall of Islamist President on January 24, 2012 in Cairo. Police clashed with protesters in Cairo earlier, on the eve of the the second anniversary of the uprising that overthrew Hosni Mubarak, as they tried to dismantle a security barrier and called for the fall of President Mohamed Morsi. AFP PHOTO/MOHAMMED ABED (Photo credit should read MOHAMMED ABED/AFP/Getty Images)
An Egyptian young protester takes part in a protest near Tahrir Square to call for the fall of Islamist President on January 24, 2012 in Cairo. A few dozens men and youths tried to dismantle the wall of concrete blocks that blocked a street leading to Tahrir Square, focal point of demonstrations that broke out on January 25, 2010 and led to Mubarak's resignation 18 days later. AFP PHOTO/MOHAMMED ABED (Photo credit should read MOHAMMED ABED/AFP/Getty Images)
An Egyptian man carries the national flag as demonstrators stand on a wall erected by security and hurl rocks at riot police in Tahrir Square on January 25, 2013. Huge crowds are expected to demonstrate in Egypt on the second anniversary of the revolution that ousted Hosni Mubarak and brought in an Islamist government, as political tensions simmer and economic woes bite. AFP PHOTO/MOHAMMED ABED (Photo credit should read MOHAMMED ABED/AFP/Getty Images)
An Egyptian demonstrator carries a petrol bomb as he stands on a wall erected by security in Tahrir Square on January 25, 2013. Huge crowds are expected to demonstrate in Egypt on the second anniversary of the revolution that ousted Hosni Mubarak and brought in an Islamist government, as political tensions simmer and economic woes bite. AFP PHOTO/MOHAMMED ABED (Photo credit should read MOHAMMED ABED/AFP/Getty Images)
Egyptian anti-riot forces block the entrance to the presidential palace in Cairo, Egypt, Friday, Jan. 25, 2013. Authorities expect a violent anniversary of the 2011 uprising that toppled long-time authoritarian President Hosni Mubarak. (AP Photo/Amr Nabil)
Egyptian protesters try to tear down a cement wall built to prevent them from reaching parliament and the Cabinet building near Tahrir Square, in Cairo, Egypt, Thursday, Jan. 24, 2013. EgyptÃs black-clad riot police fired tear gas in fierce dawn clashes with dozens of protesters. The violence which was soothed hours later in central Cairo comes on eve of the second anniversary of EgyptÃs Jan. 25 uprising, which toppled longtime authoritarian president Hosni Mubarak in 2011. (AP Photo/Hussein Tallal)
Egyptians flee teargas during a clash with police in Tahrir Square in Cairo on Thursday Jan. 24, 2013, the eve of the the second anniversary of the uprising that overthrew Hosni Mubarak.(AP Photo/Tribune Review, Jusstin Merriman) PITTSBURGH OUT
Egyptian protesters tear down a cement wall built to prevent them from reaching parliament and the Cabinet building near Tahrir Square, in Cairo, Egypt, Thursday, Jan. 24, 2013. EgyptÃs black-clad riot police fired tear gas in fierce dawn clashes with dozens of protesters. The violence which was soothed hours later in central Cairo comes on eve of the second anniversary of EgyptÃs Jan. 25 uprising, which toppled longtime authoritarian president Hosni Mubarak in 2011. (AP Photo/Hussein Tallal)
Egyptian protesters try to tear down a cement wall built to prevent them from reaching parliament and the Cabinet building near Tahrir Square, in Cairo, Egypt, Thursday, Jan. 24, 2013. EgyptÃs black-clad riot police fired tear gas in fierce dawn clashes with dozens of protesters. The violence which was soothed hours later in central Cairo comes on eve of the second anniversary of EgyptÃs Jan. 25 uprising, which toppled longtime authoritarian president Hosni Mubarak in 2011. (AP Photo/Hussein Tallal)
A Protester moments before throwing a Molotov cocktail toward Egyptian riot police, unseen, near Tahrir Square in Cairo, Egypt, Thursday, Jan. 24, 2013. EgyptÃs black-clad riot police fired tear gas in fierce dawn clashes with dozens of protesters on Thursday when they tried to tear down a cement wall built to prevent demonstrators from reaching parliament and the Cabinet building. The violence which was soothed hours later in central Cairo comes on eve of the second anniversary of EgyptÃs Jan. 25 uprising, which toppled longtime authoritarian president Hosni Mubarak in 2011. (AP Photo/Mostafa El Shemy)
An Egyptian demonstrator holds up an empty tear gas canister during a protest in Tahrir Square on January 25, 2013. Huge crowds are expected to demonstrate in Egypt on the second anniversary of the revolution that ousted Hosni Mubarak and brought in an Islamist government, as political tensions simmer and economic woes bite. AFP PHOTO/MOHAMMED ABED (Photo credit should read MOHAMMED ABED/AFP/Getty Images)
Egyptian demonstrators attend Friday prayers during a protest in Tahrir Square on January 25, 2013. Huge crowds are expected to demonstrate in Egypt on the second anniversary of the revolution that ousted Hosni Mubarak and brought in an Islamist government, as political tensions simmer and economic woes bite. AFP PHOTO/MOHAMMED ABED (Photo credit should read MOHAMMED ABED/AFP/Getty Images)
Egyptian protesters look at riot police through gaps in a wall standing for a security barrier near Tahrir Square as they try to dismantle it during a protest to call for the fall of Islamist President on January 24, 2012 in Cairo. A few dozens men and youths tried to dismantle the wall of concrete blocks that blocked a street leading to Tahrir Square, focal point of demonstrations that broke out on January 25, 2010 and led to Mubarak's resignation 18 days later. AFP PHOTO/MOHAMMED ABED (Photo credit should read MOHAMMED ABED/AFP/Getty Images)
Egyptian protesters try to tear down a cement wall built to prevent them from reaching parliament and the Cabinet building near Tahrir Square, in Cairo, Egypt, Thursday, Jan. 24, 2013. EgyptÃs black-clad riot police fired tear gas in fierce dawn clashes with dozens of protesters. The violence which was soothed hours later in central Cairo comes on eve of the second anniversary of EgyptÃs Jan. 25 uprising, which toppled longtime authoritarian president Hosni Mubarak in 2011. (AP Photo/Hussein Tallal)