Worst-case scenario

DAMASCUS, Syria - The bombing of a major Shia Muslim shrine in Iraq on Wednesday was the fuse that lit a powder keg of sectarian conflict which has been brewing for over two years.

In recent months, the warning signs of sectarian warfare could be seen everywhere in Iraq: clerics assassinated outside their mosques, dozens of people executed and dumped into ditches, and car bombers inflicting heavy casualties on the country's Shia majority.

As the attacks on Shia institutions and leaders mounted, Shias seethed and senior clerics had a difficult time restraining the community's anger. When insurgents set off bombs Wednesday that destroyed a Shia shrine in the northern Iraqi city of Samarra, the anger boiled over, and Shias unleashed a wave of violence against Sunnis.

It is the worst-case scenario that many Iraqis have feared since the insurgency's early days: persistent attacks on Shias would drive their militias to seek revenge against Sunni civilians, prompting a new cycle of violence that could destroy any hope of dampening the insurgency and bringing Sunnis into the political process.

"If this wave of violence and retaliation is not contained, Iraq could deteriorate even worse than we could imagine," said Hazem Shammari, a political science professor at Baghdad University. "The term 'civil war' would not be enough to describe it."

Since early 2004, insurgents have targeted Shia mosques, wedding parties and religious ceremonies across Iraq. They also have relentlessly attacked the Shia-dominated police and army. While there is no exact death toll, several thousand Shias are believed to have been killed by insurgent bombings and other attacks.

Iraq's most revered Shia cleric, Grand Ayatollah Ali al-Sistani, has long urged his followers not to retaliate against Sunnis. But as attacks on Shia civilians mounted, Shia militias and vigilantes began to fight back last year with tit-for-tat killings. Some Shia militias operate within Iraqi security forces.

Iraqi leaders warn that a sectarian conflict would fulfill the goals of Islamic militant Abu Musab al-Zarqawi. They point to a January 2005 letter purportedly written by al-Zarqawi in which he appealed to Osama bin Laden for help in setting off a civil war through a campaign of bombings against Shia institutions. Al-Zarqawi argued that car bombings alone were not enough to plunge Iraq into a full-scale war: The attacks needed to prompt a Shia backlash.

"So the solution, and only God knows, is that we need to bring the Shia into the battle," said the letter, which was intercepted by Kurdish security officials. "It is the only way to prolong the duration of the fight between the infidels and us."

The Sunni-Shia struggle in Iraq is largely political. Sunni Arabs had dominated the country since its independence in 1932, despite making up only a fifth of Iraq's population. Saddam Hussein's regime brutally repressed the Shias, who constitute 60 percent of the country's 25 million people.

After the U.S. invasion in March 2003, Sunnis began to lose their grip on power. Most Sunnis boycotted the first parliamentary election in January 2005, either as a protest or for fear of the insurgents. Only 17 of the 275 members in that parliament were Sunnis, and Sunnis complained that they were also underrepresented in the cabinet set up by Prime Minister Ibrahim al-Jaafari. Like parliament, it was dominated by the two blocs that swept the election: Shia religious groups and Kurdish secular parties.

Sunnis took part in the Dec. 15 elections, in which Iraqis elected a legislature that will serve a four-year term. In the new parliament, Sunnis won 55 seats.

But two months after the election, there is still no new government in place, and negotiations are stalled over who will be prime minister. The deadlock over divvying up positions - which also occurred after the January 2005 election - is frustrating to many Iraqis, who argue that leaders should instead be focusing their energies on dealing with the insurgency.

"The Iraqi people want to see improvement in security and in their daily lives," said Nabil Salim, a political analyst in Baghdad. "But these political leaders are spending most of their time on political maneuvering."

After Shias began attacking Sunni mosques and neighborhoods Wednesday, leaders of the main Sunni political parties cut off negotiations with Shia and Kurdish parties about joining the new government. That could prove to be a devastating setback for efforts to halt the insurgency. The insurgents are a mix of Islamic militants from neighboring countries and Iraqi Sunnis, who formed the backbone of Hussein's regime.

If the wave of anti-Sunni violence unleashed by the Samarra bombing continues, then al-Zarqawi will have fulfilled one of his main goals: sowing sectarian chaos in Iraq.

It is unclear whether al-Sistani and Shia politicians will be able to restrain Shia militants. One such force is the militia loyal to renegade Shia cleric Muqtada al-Sadr, which fought extended battles twice in 2004 with U.S. forces. Al-Sadr's militia surrendered most of its weapons to the Iraqi government, but its members are still difficult to control because they do not look to senior clerics such as al-Sistani for guidance. "Al-Sadr is going to play a key role," Salim said. "He could inflame the situation or calm it down."

Shia and Sunni Muslims

Wednesday's attack on the Askariya shrine in Samarya has escalated tensions between Shila and Sunni Muslims in Iraq.

What Shia believe: