In an unusual briefing before the House Foreign Affairs Committee Thursday, a disguised Syrian defector shared photos he had taken before fleeing the war-torn country that document what appears to be widespread atrocities carried out by the regime of Syrian President Bashar al-Assad. The gruesome imagery depicting starved corpses and tortured bodies prompted criticisms by lawmakers, including Democrats, that Barack Obama's administration isn't doing enough to end Assad's reign of terror.

The anonymous Syrian defector known only as "Caesar" testified before the committee while wearing a blue hooded parka with a baseball cap and sunglasses. Speaking through an interpreter, Caesar identified himself as a former photographer for the Syrian military police. Caesar said he was tasked with photographing images to verify that Syrian military personnel were carrying out the orders of top brass. Inside the hearing room, flat-screen TVs flashed images of emaciated bodies and poster stands showcased enlarged photos of mangled corpses.

The Syrian military photographer fled his country last year and handed thousands of photos to the United Nations and to FBI investigators. His photographs, which U.S. officials say are authentic, show some 11,000 mutilated and mangled bodies. The Syrian government dismisses the photographs as fakes.

"I have seen horrendous pictures of bodies of people who had tremendous amounts of torture, deep wounds and burns and strangulation," said Caesar.

Lawmakers, who appeared visibly shaken by the photographs, said the disturbing images were further evidence that the administration erred by failing to arm moderate members of the Syrian opposition sooner. The criticism came from both parties, with White House allies joining in the attacks.

"If we had taken that approach a year and a half ago, we may have been able to stem the growth of ISIS [the Islamic State of Iraq and al-Sham] and weaken the regime of Bashar Assad," Rep. Eliot Engel, the most senior Democrat on the committee, said. "But we didn't, unfortunately."

The White House has belatedly tried to bolster the rebels through moves like a new plan to provide moderate members of the Syrian opposition with $500 million worth of weapons, equipment, and training run by the Pentagon. Freeing up the money requires authorization from Congress, but many key lawmakers outside the Foreign Affairs Committee remain deeply skeptical of the White House's plan due to concerns about arming radical jihadists, further embroiling the United States in a distant civil war, and writing the White House a blank check subject to only modest congressional scrutiny.

Supporters of the Syrian opposition in Washington hope that the gruesome images will catalyze efforts to boost U.S. military support for Syria's moderate opposition. The briefing was in part facilitated by the Coalition for a Democratic Syria, an umbrella group that lobbies for additional U.S. support to the rebels. 

"This brings it to a whole new level," Oubai Shahbandar, an advisor to the Syrian Opposition Council, told Foreign Policyafter the briefing. "This is genocide with a capital 'G.' You can't ignore this. You can't say there are no good options. We have rows and rows and rows of naked emaciated bodies." 

The Obama administration's commitment to arming the Syrian rebels is currently at a significant crossroads. 

The CIA is currently providing training and small arms to rebels in Jordan who have been vetted for potential ties to extremists while Washington allows Persian Gulf countries to provide anti-tank missiles. The CIA program has been criticized as too modest to make an impact on the battlefield, where pro-Assad forces have been steadily reclaiming lost territory and seem poised to reconquer Aleppo, the first major city taken by the rebels. It's unclear whether Caesar's brutal imagery will succeed in bolstering the case for further intervention. 

The Foreign Affairs Committee has provided some of Caesar's imagery below. (Warning: The images are intensely graphic and violent in nature. Click to see uncensored versions.)