As the debate over the United States' potential military intervention in Syria rages on, a new video smuggled out of Syria shows that the rebel forces have demonstrated the same capacity for brutality as the regime they are trying to overthrow. 

The video shows Syrian rebels standing over seven soldiers from Bashar al-Assad's military. The soldiers laid with their faces in the dirt and their bare backs covered with red bruises.

"For fifty years, they are companions to corruption," says Abdul Samad Issa, the commander of the rebels in the video. "We swear to the Lord of the Throne, that this is our oath: We will take revenge."

Issa then shoots one of the prisoners in the back of the head, and his men follow suit. One of Issa's former aides smuggled the video out of the war-torn country and told The New York Times that Issa's motivation in joining the rebellion has been based on revenge and on the "extermination" of the Alawites, the Islamic sect to which Assad belongs.

The video adds to concerns among U.S. officials that aiding the rebels will allow Islamic extremists to increase their control on Syria. Two groups, the Nusra Front and the Islamic State In Iraq and Syria, have U.S. officials particularly worried due to their ties to Al-Qaeda.

Secretary of State John Kerry told Congress on Wednesday that only "15 to 25 percent" of the rebel forces are extremists, but Representative Michael McCaul (R-Tx.), told Kerry that he had been told in briefings that half of the rebels were estimated to be extremists.

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Time Magazine's Aryn Baker reports that anti-Assad activists are growing worried that the extremists' military prowess and resources, including combatants who had previously fought in Iraq, will give them the influence needed to hijack the rebel movement with their own Islamic agendas. They fear that this could result in Syrian citizens abandoning the rebel cause and reaffirming their support for Assad.

"They repaint our graffiti with Islamic paintings and they want to solve our problems in Islamic courts," said one rebel. "I want a national and civil court.”