Insurgent groups, supported by certain Western states and their regional allies, such as Qatar, Saudi Arabia, and Turkey, have been trying to topple the Syrian government for over 20 months.
Several international human rights organizations have accused the foreign-sponsored insurgents of committing war crimes.
New video footage has surfaced online showing foreign-backed insurgents in Syria killing 10 unarmed Syrian prisoners.
The video, posted on the internet on Thursday, shows 10 men lying face down next to a lookout tower and a building.
"I swear to God that we are peaceful," pleads one of the men to the camera. In response, the insurgents shot him in the arm. Then more shots are fired and his body goes into spasms.
The video, which appears to have been filmed by an insurgent, shows that even before the shooting, two of the men are not moving and one has blood coming from his chest.
Comments accompanying the video indicate that it was filmed in Ras al-Ain, a town near the Turkish border, which has been the scene of heavy clashes in recent weeks.
The footage cannot be independently verified.
The Syria crisis began in March 2011.
The Syrian government says that the chaos is being orchestrated from outside the country, and there are reports that a very large number of the insurgents are foreign nationals.