Amid a wave of attacks on Syrian government facilities in Damascus yesterday, a massive car bomb hit a security checkpoint in the central Damascus neighborhood of Mazraa. It killed at least 53 people and wounded 235, according to both Syrian state media and US-backed Syrian opposition sources.

This is the latest in a series of terrorist atrocities against Syrian civilian or government targets, many of which have been openly claimed by US-backed armed opposition groups and hailed in the US media as victories in Washington’s proxy war to oust Syrian President Bashar al-Assad.

The bomb went off at around 10:30 AM on Al-Thawra Street, a busy street near the headquarters of the ruling Baath Party and the embassy of Russia, a key backer of the Syrian regime. The site is also close to a medical clinic and a school, and many children were reportedly killed.

An area shopkeeper described to the BBC how a young girl was killed by flying glass when the blast hit: “Everything in the shop turned upside down. I pulled her inside the shop, but she was almost gone. We couldn’t save her. She was hit in the stomach and head.”

Three other car bombs in Damascus’ northeastern Barzeh neighborhood struck a police station, a telecommunications surveillance facility and a drug enforcement agency. Mortar fire also hit Syrian Army General Staff headquarters.

Syrian security forces reportedly stopped an attempted second car bombing by a driver in a vehicle packed with 1,500 kilograms (3,306 pounds) of high explosives.

As of this writing, no organization has claimed responsibility for the bombings. However, earlier this month the Al Nusra Front, an Al Qaeda-linked group within the US-backed anti-Assad opposition, pledged to mount an offensive to “liberate Damascus.”

The day before the bombing, a group of jihadists from the Caucasus arrived in Syria and posted a video on the opposition Free Syrian Army’s (FSA) Facebook page. The FSA commented that the group intended to fight in Syria under the banner of the Al Nusra Front. In the video, the leader of the group, the Battalion of Immigrants to Syria, spoke in Russian and pledged to “achieve one of two goods, either victory or martyrdom.”

The Al Nusra Front—which grew out of an Al Qaeda group in US-occupied Iraq that carried out similar bombings—has emerged over the last year as a key tool of the Western policy of stoking up a sectarian civil war in Syria. It claimed responsibility for the May 2012 double-suicide bombings in Damascus that killed 55 and wounded 372.

Since then, the Syrian capital has been the target of repeated terror bombings aimed at civilians. These include two car bombings in November 2012 in the al-Worod and Mezzah Jabal areas, killing 22 and injuring several dozen; a December 2012 car bombing in the Ish al-Warwar neighborhood, killing three, including two children, and injuring 35; and a January 14, 2013 bombing near Hamish Hospital.

The New York Times praised another Damascus bombing by the Islamist opposition—the July 18, 2012 bombing that killed Syrian Defense Minister Dawould Rajha, Security Advisor Hasan Turkmani, and Assad’s brother-in-law, Assef Shawkat—as a “potent blow in the struggle for Syria.”

Seen in this context, the attempts by Western-backed Syrian opposition forces to distance themselves from the Al Nusra Front and yesterday’s bloody bombing reek of hypocrisy and deceit.

The National Coalition for Syrian Revolutionary and Opposition Forces (NSCROF), the main umbrella group for the Western-backed opposition, wrote on its Facebook page: “Any acts targeting civilians with murder or human rights violations are criminal acts that must be condemned, regardless of the perpetrator or justification.”

However, the opposition is not pulling back from endorsing yesterday’s bombing because they have cut their ties to Al Nusra and its allies, or because they oppose the bloody terror bombings through which the US and its allies have fought their proxy war in Syria. They are seeking to curry favor with imperialist powers concerned at the prospect of installing an openly Al Qaeda-aligned regime in Syria.

In congressional testimony on February 7, US Defense Secretary Leon Panetta and the chairman of the Joint Chiefs of Staff, Gen. Martin Dempsey, said that President Barack Obama had overruled their proposals to more aggressively arm the Syrian opposition. US officials indicated that the White House feared that if opposition fighters received anti-air missiles and other high-tech weaponry from the US, these weapons could be turned against Israeli or American targets. (See: “Pentagon chiefs reveal divisions over Syria”).

There are continuing divisions within the US-led camp over how aggressively to arm the Syrian opposition. While on Monday the European Union (EU) voted to extend its arms embargo on Syria, the Al Thani monarchy in Qatar announced plans on Wednesday to donate a further $100 million to arm the NCSROF. In talks with Qatari heir apparent Sheikh Tamim bin Hamad Al Thani, British Foreign Secretary William Hague pledged that Britain would continue to seek to “amend” the EU embargo.

Earlier this week, the Obama administration itself indicated that it could reconsider its decision not to give high-tech weaponry to the Syrian opposition. An unnamed senior administration official told the New York Times, “This is not a closed decision. As the situation evolves, as our confidence increases, we might revisit it.”

Washington is also exploring plans to put the anti-Assad opposition in power through a negotiated settlement with sections of the Assad regime. It has supported Syrian opposition leader Moaz Al Khatib’s proposal to hold talks with Syrian Vice President Farouq Al Sharaa. This has led to significant conflicts within the anti-Assad opposition.

Reuters commented: “Al Khatib formulated the initiative in broad terms last month after talks with the Russian and Iranian foreign ministers in Munich but without consulting the [opposition] coalition, catching the umbrella organization by surprise. A powerful bloc in the coalition dominated by the Muslim Brotherhood, the only organized group in the political opposition, criticized the initiative as harming the opposition.”

Syrian opposition groups met for a conference in Cairo yesterday to discuss the proposal. They drafted a communiqué backing peace talks held under American and Russian auspices, but insisting that Assad could not be a party to the negotiations.

In the meantime, the FSA is stoking up conflict throughout the region. Yesterday it announced that it had shelled forces of the Lebanese Hezbollah militia along the Lebanese-Syrian border. It also issued an ultimatum to Hezbollah, giving it 48 hours to cease operations in Syria or face FSA attacks in southern Lebanon.