BEIRUT -- A Syrian peace plan brokered by the Arab League unraveled Friday as security forces killed 15 people, opening fire on thousands of protesters who denounced President Bashar Assad and said he never intended to hold up his end of the deal to end the violence.
The bloodshed, only two days after Syria agreed to the deal, suggests Damascus is unwilling -- or unable -- to put a swift end to a crackdown that already has killed 3,000 people since the uprising began in March.
"This regime is not serious about ending its brutal crackdown," said Mustafa Osso, a Syria-based human rights lawyer. "Today was a real test for the intentions of the regime and the answer is clear to everyone who wants to see."
The crisis in Syria has burned for nearly eight months despite widespread condemnation and international sanctions aimed at chipping away at the ailing economy and isolating Assad and his tight circle of relatives and advisers. The protesters have grown increasingly frustrated with the limits of their peaceful movement, and there are signs of a growing armed rebellion in some areas.
Some protesters even are calling for the kind of foreign military action that helped topple Libyan dictator Moammar Gadhafi.
But NATO has ruled out any plans for Syria, a country of 22 million with a combustible mix of sectarian and religious identities, and Assad still has a firm grip on power. The iron loyalty of his security apparatus sets the stage for an increasingly destructive fight over the future of a nation ruled for more than four decades by the Assad dynasty.
Tremors from the unrest in Syria could shake the region. Damascus' web of allegiances extends to Lebanon's powerful Hezbollah movement and Iran's Shiite theocracy. And although Syria sees Israel as the enemy, the countries have held up a fragile truce for years.
Thousands of protesters braved cold and rainy weather Friday after opposition groups called for a large turnout to test whether the regime would in fact refrain from using deadly force, as agreed under the Arab League plan. But gunfire erupted shortly after the protests began, following the same pattern seen during previous Friday protests for months.
"Arab League, beware of Bashar Assad!" read one banner carried by protesters in the central city of Homs, which has turned into one of the country's most deadly areas due to the military crackdown and what appears to be growing sectarian bloodshed.
Two main activist groups, the British-based Syrian Observatory for Human Rights and the Local Coordinating Committees, said at least 15 people were killed Friday, most of them in Homs and suburbs of the Syrian capital.
The violence was a blow to the 22-nation Arab League, which announced Wednesday that Damascus had agreed to a broad peace plan that also called for the Syrian government to pull tanks and armored vehicles out of cities, release political prisoners and allow journalists and rights groups into the country.
Officials from the Cairo-based Arab League could not be reached for comment Friday, the start of a holiday weekend.
The plan presented flaws at the outset, in part because it did not provide for any repercussions if the regime reneges on its commitments. There also was no mention of any on-the-ground monitoring to supervise the regime's actions.
The government has largely sealed off the country from foreign journalists and prevented independent reporting, making it difficult to confirm events on the ground. Key sources of information are amateur videos posted online, witness accounts and details gathered by activist groups.
The structure of Syria's security forces also could prevent any immediate end to the violence.
Assad, and his father before him, stacked key military posts with members of their minority Alawite sect, ensuring the loyalty of the armed forces by melding their fate with that of the regime.
If the regime falls, the argument goes, the country's Sunni majority gains the upper hand and the Alawites lose their privileged status. Although there have been army defections, they appear to be mostly Sunni conscripts, not high-level commanders. Adding to the violence are the shabiha, the mafia-style network of young Alawite men who act as enforcers for the regime.
The Syrian deadlock, in many ways, is rooted in the country's sectarian divide.
The Alawites rose from economic obscurity after the 1970 coup led by Bashar Assad's father, Hafez, gaining power and financial muscle in exchange for loyalty to the Assads. It is their support that the younger Assad sees as the key to continued power.
Alawites claim they would be oppressed as Muslim heretics if the Sunnis come to power, and Sunnis claim they are unable to get the government jobs essential to reach the lower rungs of the middle class.
The now-privileged Alawites, along with other minority groups who feel protected under the Assad regime, would see majority rule as a risk at best, a nightmare at worst.
Syria blames the bloodshed on "armed gangs" and extremists acting out a foreign agenda to destabilize the regime. Assad has played on some of the countries worst fears to rally support behind him, painting himself as the lone force who can ward off the kind of radicalism and sectarianism that have bedeviled neighbors in Iraq and Lebanon.
On Friday, Syria's Interior Ministry gave one week for anyone who was involved in carrying, selling, buying or distributing arms to turn themselves in and benefit from a pardon.
Analysts say Assad's support is waning, and his backers are often motivated by little more than fear.
In a report this week, the International Crisis Group said the support "is almost entirely of a negative sort: fear of sectarian retribution, Islamism, foreign interference, social upheaval or, more simply, anxiety about the unknown."