Insurgents attacked the golden-domed Al-Askariya mosque in Samarra early today, striking a major blow to American and Iraqi efforts to calm the rising violence in Iraq.
It follows a February 2006 attack on the same mosque that is widely cited as the event that started a fledgling civil war.
In the first attack, an explosion brought down the mosque's famous dome, which Shiites revere as the burial place of two imams considered direct descendants of Muhammad. Today, crowds gathered around the mosque after two morning blasts toppled the two remaining minarets.
In March 2006, President Bush said the first attack -- believed to have been carried out by al Qaeda -- had "changed the nature of the conflict in Iraq." In the aftermath of the first attack, Shiite death squads targeted Sunnis, whose bodies were often found bound and showing signs of torture, throughout Baghdad. Sunni bombers attacked Shiite markets and other gathering places.
The resulting violence prompted Bush to send in the so-called "surge" of 30,000 additional troops to Iraq. Days after the last of the surge troops have arrived in Iraq to calm sectarian tensions, however, today's mosque attack threatens to increase the violence.
The Iraqi government now expects trouble and has convened a rare meeting of the Iraqi Security Council. An emergency curfew begins at 6 p.m.
Ali al-Sistani, Iraq's top Shiite religious leader, urged Shiites not to commit acts of reprisal against Sunnis. Prime Minister Nouri Kamel al-Maliki, bracing for a new wave of violence, asked U.S. Ambassador Ryan Crocker and Gen. David Petraeus, the top U.S. commander in Iraq, to reposition American reinforcements to aid Iraqi troops.
Prime Minister Maliki also visited the mosque today to inspect the damage.
Petraeus and Crocker condemned the attack in a joint statement.
"This brutal action on one of Iraq's holiest shrines is a deliberate attempt by al Qaeda to sow dissent and inflame sectarian strife among the people of Iraq. It is an act of desperation by an increasingly beleaguered enemy seeking to obstruct the peaceful political and economic development of a democratic Iraq," the statement said.
Despite the widespread calls for peace, there were some early ominous signs. Hours after the attack, sporadic gunfire broke out near the heavily fortified Green Zone. Gunmen attacked a Sunni mosque in Baghdad's al-Bayaa neighborhood, a recent hotbed for sectarian violence.