A border region with a history of hostility toward the Syrian regime is posing the biggest challenge yet for President Bashar Assad's struggle to crush the revolt against his family's 40-year-rule.
Analysts say Assad will do anything to restore control in the restive northern area bordering Turkey, where mutinous forces are giving a largely peaceful revolt new strength - and firepower.
Human rights groups say more than 1,400 people have died in the government crackdown since the uprising erupted in southern Syria in mid-March.
On Saturday tanks and thousands of forces believed to be led by President Assad's brother sealed the roads leading to the mostly deserted town of Jisr al-Shughour in response to what the government claims were attacks by "armed groups" that killed more than 120 officers and security personnel last week. Refugees reaching Turkey said the chaos erupted as government forces and police mutinied and joined the local population.
Syrian soldiers and police officers who deserted rather than fire on protesters remained behind to fight against an expected all-out government assault, a resident said, and unarmed demonstrators were ready to fight "with their hands" in the town just 12 miles from the Turkish border.
Soldiers loyal to the regime reportedly came under sniper fire as they approached.
Ausama Monajed, a London-based Syrian activist, said the Assads could be worried not just about army defections, but any hesitation to obey shoot-on-sight orders.
"The Assads are reshuffling the army and creating a number of mainly Alawite units made up specifically of people who have been tested and have shown themselves to be hardcore loyalists," he said.
"It is these units that have been sent to Jisr al-Shughour."
Residents and activists reported heavy gunfire in the Qarqouz village, about 4 miles from Jisr al-Shughour, after the army and security forces stormed in, but there were no immediate reports of casualties.
The Obama administration today strongly condemned what it called the "outrageous use of violence" by the Syrian government and demanded an immediate end to its brutality - which included Syrian security forces shooting, assaulting and arresting demonstrators.
"It's this kind of appalling violence that leads the United States to support a U.N. Security Council Resolution condemning the Syrian government's actions and calling for an immediate halt to the violence and abuse of basic human rights," the White House said.
Syrian Foreign Minister Walid Moallem called on the United Nations to help his country fight "terrorist groups." In an interview he gave to the Syrianow website, Moallem said he had sent an urgent message to the U.N. chief warning that any Security Council resolution targeting Syria would be considered "intervention in his country's internal affairs."
On Friday, a U.N. spokesman said Assad was avoiding U.N. Secretary General Ban Ki-moon's calls.
Authorities said they have made some arrests and killed and wounded many of the armed men around Jisr al-Shughour, a city of about 40,000 that has been largely abandoned by residents afraid of a coming government attack.
About 80 percent of the population has fled, with more than 4,000 Syrians taking sanctuary across the nearby Turkish frontier.
Jamil Saeb, an activist from the town who was reached by phone, suggested the army was afraid to take on the people who stayed behind because Jisr al-Shughour is "known to be exceptionally fierce." He said several army deserters and officers were still there and have vowed to protect unarmed residents.
Jisr al-Shughour and the province of Idlib have a history of animosity toward the regime, which until recently has maintained tight control over its people. The town's Muslim Brotherhood population rose up against Assad's father, the late president Hafez Assad, in the late 1970s. It came under heavy government bombardment in 1980, with a reported 70 people killed. Residents say the numbers were much higher.
The events proved a prelude to a 1982 three-week bombing campaign against the city of Hama that crushed a Sunni uprising there, killing 10,000 to 25,000 people, according to Amnesty International estimates.
"They (regime) have a grudge against Jisr al-Shughour since the '80s," Saeb said.
"We hope we will not have to take up weapons," he added, saying remaining residents were so far insisting on "peaceful resistance." Saeb spoke using a Turkish mobile phone from a town only few miles from the border.
Confirming information out of Syria is difficult. Communications are cut in areas where the uprising is strongest, including Jisr al-Shughour. Syrians who speak openly face retribution from the regime, and foreign journalists have been expelled.
Undaunted by the continuing and brutal crackdown, protests extended to every major city Friday, and activists said 36 people were killed when security forces opened fire during demonstrations across the country. The dead included 20 from the northern Idlib province, home to Jisr al-Shughour.
Twenty-five miles to the southeast in the town of Maaret al-Numan, thousands of protesters overwhelmed security forces and torched the courthouse and police station. The army responded with tank shells, a Syrian opposition figure told The Associated Press by telephone, speaking on condition of anonymity, fearing retribution.
Syrian TV appeared to confirm at least part of the report, saying gunmen opened fire on police stations, causing casualties among security officials.
Backed by helicopters and tanks, the troops responsible for most of Friday's violence were believed to be from an elite division commanded by Assad's younger brother, Maher. The decision to mobilize his unit against the most serious threats to the Assad regime could be a sign of concern about the loyalty of regular conscripts.
Syria's brutal crackdown has angered the leader of neighboring Turkey, who accused the Assad regime of "savagery."