BEIRUT - A suicide bombing that killed members of President Bashar Assad's inner circle as fighting raged in the Syrian capital on Wednesday increased the urgency for tougher United Nations action, Western leaders said, a stance rejected by Russia.The bomb that killed Syria's defense minister and Assad's brother-in-law will weaken morale and might accelerate high-level defections, but does not signal the president's imminent downfall, analysts said. US Defense Secretary Leon Panetta said on Wednesday that the situation in Syria appeared to be "spinning out of control," as he voiced concern about rising violence and renewed calls for increased global pressure on Assad to step down."This is a situation that is rapidly spinning out of control," Panetta said, adding the international community needed to "bring maximum pressure on Assad to do what's right, to step down and allow for that peaceful transition."British Foreign Secretary William Hague condemned the suicide attack, and said it "confirms the urgent need for a Chapter 7 resolution of the UN Security Council on Syria".The UN Security Council was due to vote later on Wednesday on a resolution, proposed by Britain, the United States, France and Germany, that would extend a UN observer mission in Syria for 45 days and place international envoy Kofi Annan's peace plan under Chapter 7 of the UN Charter.Chapter 7 allows the 15-member council to authorize actions ranging from diplomatic and economic sanctions to military intervention. US officials have said they are talking about sanctions on Syria, not military intervention."The situation in Syria is clearly deteriorating. All the members of the UN Security Council have a responsibility to put their weight behind the enforcement of Joint Special Envoy Kofi Annan's plan to end the violence," Hague said.German Chancellor Angela Merkel said the bombing "shows us that it is high time to ratify the next UN resolution."French Foreign Minister Laurent Fabius said Paris would push for the resolution. "Given this degree of violence, it means that it is necessary and urgent to find a political transition that allows the Syrian people to have a government that expresses its aspirations."'Decisive battle'But, with four straight days of fighting in Damascus - some within sight of the presidential palace on Wednesday - Moscow said the draft resolution would worsen the violence."A decisive battle is under way in Syria," Foreign Minister Sergei Lavrov told journalists in Moscow. "It is a dead end policy to support the opposition. Assad will not go on his own and our Western partners don't know what to do about that."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 signalling 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 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 bombing, claimed by the Free Syrian Army (FSA) and also by Islamist group Liwa al-Islam, does not alter the fact that the rebels remain hugely outgunned by Assad's forces."These are very significant developments, but I believe the offensive will be repelled," Skinner said. "Psychologically, though, this will likely give the FSA a significant boost and may also precipitate more defections at a senior level."