Syria's rebel fighters vow no mercy for their own pro-regime family members

It's been nearly a month since Abu Saddam, a rebel fighter, last spoke with his brother, who fights on the side of the regime as a special forces soldier in Damascus, Syria. They feared that the phone call was being monitored, so they spoke in code as Abu Saddam tried to gauge if his brother was prepared to defect and join him in the ranks of the rebels' Free Syrian Army (FSA).

At the time, Abu Saddam says, his brother sounded ready, but a month later his brother is still with the government.

"If my brother does not leave the Army, I swear I will kill him," says Abu Saddam, who asked to use his nickname for security reasons. "We are fighting people who are fighting against our Sunni religion and supporting a criminal regime that doesn't differentiate between fighters and women and children."

Like many FSA fighters on the front lines, Abu Saddam describes his commitment to toppling the Assad regime as a quest more important than family. The Syrian uprising has devolved into a bloody civil war, pitting brother against brother, dividing families and communities in a way that may leave scars lasting long after the fighting ends.

For much of the uprising, Aleppo, a bastion of pro-Assad supporters, remained relatively quiet. But when fighting finally erupted there in late July, the city became the center of the conflict, tearing families apart.

In Aleppo's Old City, Abu Mohammad (also a nom de guerre), the leader of a local FSA unit, says his troops are mostly battling pro-government militias. Many of the men in his unit, the Grandsons of Saladin, grew up in the city and say they have friends and family who are still loyal to the government.

"The most important thing now is the cause. It's more important than family," Abu Moham­mad says.

Recently, one of his soldiers, Mo­hammad Zakariah Hidad, learned that his cousin, a member of a pro-regime militia, was killed in a nearby battle with the FSA. Mr. Hidad says he was never close with his cousin, who he says terrorized protesters as a pro-government thug during the uprising. When Hidad reached the street where his cousin was killed, the battle was still ongoing, so he could only see the body with binoculars.

"I was very happy when I saw his body. I called another person in his militia whose phone number I had and told him Mahmoud [my cousin] was dead, and if he keeps fighting for [President Bashar al-] Assad, he will be next," he says. "Because my cousin is dead it means that there is one less devil man."

Meanwhile, the divide between Syria's sectarian groups appears to be deepening. The FSA draws its members from most ethnic groups throughout Syria, but many Sunni Muslims in the FSA now describe themselves as engaged in a struggle to protect their religion from the country's Alawites, an offshoot of Shiite Islam which Assad and his closest supporters follow.

Even though there are Alawites who have defected, Abdu Abu Mohammad, a Sunni opposition fighter, says, "It’s impossible to have a Shiite with us."

Referencing Hezbollah, the Lebanese Shiite militant group that has supported the Assad regime, he adds, "Everyone who is a Shiite is with Hezbollah and Hezbollah is with Assad. For us as Sunnis, there is no problem with Shiites or other religions, but the Shiites say 'If you kill a Sunni, you will go to heaven'."