A suicide bomber killed Syria’s defense minister and President Bashar Assad’s brother- in-law in Damascus on Wednesday.The bomber, apparently an insider and possibly a trusted bodyguard, struck at the daily meeting attended by ministers and senior security officials at the National Security building as battles raged inside Damascus, within sight of the nearby presidential palace.The bomb that killed Rajha, Shawkat and Turkmani will weaken morale and might accelerate high-level defections, but does not signal the president’s imminent downfall, analysts said.Two rebel groups scrambled to claim responsibility for the explosion, hailing it as successful strike at the heart of the government.Shortly after news of the attack broke, the Lebanese Broadcasting Channel news site reported that Liwa al-Islam (The Brigade of Islam), a Syrian rebel Islamist group, had claimed it carried out the bombing.“We are happy to inform the people of Syria and also the people of the capital that thanks to God we targeted the National Security building, which includes what is called the crisis management cell, in the capital Damascus,” the group said in a statement on its Facebook page.“The explosive charge was laid by the Sayyed al-Shuhada brigade of Liwa al-Islam, during a meeting of the senior gang of criminals of the regime and its pillars,” the statement continued.The Free Syrian Army also claimed responsibility for the attack, according to Col. Qassim Saad el-Din, a spokesman. “This is the volcano we talked about, we have just started,” he said.Saad el-Din added that Wednesday’s bombing was “only the beginning of a long series of operations” designed to destroy Assad, his regime “and all its pillars and symbols.”The bombing targeted the National Security Bureau, Saad el-Din said, to kill “pillars of Assad’s responsible for committing brutal massacres that claimed the lives of children, women and the elderly.”A security source in Syria told Reuters that a bodyguard for the president’s inner circle had detonated explosives at a meeting of ministers and Assad’s top security and military officials.A spokesman for Liwa al-Islam confirmed the claim by telephone but denied it was a suicide attack.“Yes we did the attack, but there was no suicide bomber,” said the man, who asked to be identified as Abu Ammar. “Our men managed to plant improvised explosives in the building for the meeting. We had been planning this for over a month.”In a speech marking the sixth anniversary of the Second Lebanon War, Hezbollah chief Hassan Nasrallah said, “We express our condolences to the Syrian leadership, army and people and condemn the attack that served the enemy interests.”US Defense Secretary Leon Panetta and British Defense Secretary Philip Hammond warned that the Syrian regime would be held responsible for securing its chemical weapons.Late on Wednesday evening, the White House said the US was closely monitoring Syria’s military facilities and believed its chemical stockpile remained under government control.The Security Council has postponed until Thursday a vote on a Western-backed resolution that threatens Syrian authorities with sanctions in a bid to end the conflict, Russia’s UN envoy said on Wednesday.UN-Arab League envoy Kofi Annan had requested the delay amid differences between Moscow and the resolution’s Western sponsors over whether Damascus should be threatened with sanctions.Analyst Gala Riani said the suicide bombing was “in some ways the most successful direct attack on the regime we’ve had so far.”“I think the next few days are going to be crucial in signaling where the conflict goes from here,” said Riani, a Middle East analyst at the Control Risks consultancy.“At the very least, we can expect the situation to continue to deteriorate. But I think it will take more than this to take the Assad regime down.”The brazen attack at a meeting of top security officials and ministers in the heart of Damascus will send a message to the top members of the Syrian government that they are vulnerable.“It sends a stark message that individual ministers are not safe and is likely to accelerate the erosion of the regime’s support base,” said Anthony Skinner, head of Middle East consultancy Maplecroft.The Syrian Defense Ministry said that “this act of cowardice will only add to our resolve to combat terrorism with renewed energy.”A spokesman for the Syrian Information Ministry said: “Every country and entity that sent weapons and US dollars to Syria is a partner in this crime.”As news of the day’s began to spread, there were unconfirmed reports that Syrian troops had begun to defect en masse.Later on Wednesday afternoon, Syrian state TV reported that a new defense minister, Gen. Fahad Jassim Freij, had been appointed to replace Rajha.Freij, who was previously the chief of staff of the armed forces, is from Hama province, a center of the revolt.In the aftermath of the attack, Syrian forces hit rebel positions across the capital, state media said, shortly after Damascus vowed to punish those responsible for the bomb attack.SANA also said that armed forces had killed a large number of “terrorists” in the central Damascus neighborhood of Midan and clashed in the district of Qaboun, and later also in Selquin and Kafar Takharim.Activists in neighborhoods that have seen fighting over the past four days said that government troops and pro-government militias were flooding in to quash rebels.“There is a very heavy presence of security forces in the streets now,” said Susan Ahmad, a resident of Barzeh where rebels have been hiding out.“Apart from Assad’s forces, the streets are empty,” she added.State television broadcast footage it said was filmed on Wednesday, showing men in blue army fatigues ducking for cover and firing – the first time official media have shown clashes in the heart of the capital.Syria’s Defense Minister Daoud Rajha and Assef Shawkat, Assad’s brother-inlaw, were killed in the blast.Later on Wednesday, Syrian state television confirmed that Gen. Hassan Turkmani, a former defense minister and senior military official, had also died from wounds sustained in the attack, confirming earlier reports from security sources.Interior Minister Muhammad Ibrahim al-Shaar was wounded but stable, and intelligence chief Hisham Bekhtyar was undergoing surgery, according to a Syrian security source who spoke to Reuters.On Wednesday evening, the Syrian National Council, a coalition of opposition groups based in Istanbul, said the bombing was “a turning point in the Syrian conflict, which will be over within weeks or months.”“This is the final phase. They will fall very soon,” Abdelbasset Seida of the Syrian Free Army said in an interview in the Qatari capital Doha.“Today is a turning point in Syria’s history. It will put more pressure on the regime and bring an end very soon, a matter of weeks or months.”Western leaders said Wednesday’s bombing increased the urgency for tougher UN action, a stance rejected by Russia.