The bombing in Damascus that killed at least three top Syrian officials shows the country’s crisis is “rapidly spinning out of control,” Defense Secretary Leon Panetta said Wednesday.

US officials were unsure whether it was an insider attack, but they suggested it could mark a turning point in the 16-month conflict.

In a bid to turn up the heat, the Obama administration slapped financial sanctions on many top members in Syrian President Bashar Assad’s government, targeting the prime minister and 28 other Cabinet ministers and senior officials.

The Treasury Department announced the sanctions just hours after the bombing in Damascus.

The US move freezes any assets the ministers may have in US jurisdictions and bars Americans from doing business with them. The administration had already imposed similar penalties on security officials, but the latest step extends those sanctions to virtually the entire government.

“Today’s actions reflect the unwavering commitment of the United States to pressure the Assad regime to end the carnage and relinquish power,” said David S. Cohen, the undersecretary for terrorism and financial intelligence at Treasury. “As long as Assad stays in power, the bloodshed and instability in Syria will only mount.”

Appearing with Panetta at a Pentagon news conference, British Defense Minister Philip Hammond said the escalating violence indicates that the rebels feel emboldened and that the Assad government is suffering “probably some fragmentation around the edges” as it struggles to keep a grip on power.

“There is a sense that the situation is deteriorating and is becoming more and more unpredictable,” Hammond said.

Pointing to “increasing” defections and a “strengthened and more united” opposition, National Security Council spokesman Tommy Vietor said there was growing momentum against Assad.

“It’s clear that the Assad regime is losing control of Syria,” Vietor said, stressing the urgent need for a political transition to avoid a “lengthy and bloody sectarian civil war.”

“Many formerly pro-regime Syrians view Assad as the problem, not the solution, and the regime’s financial struggle continues,” he added, shortly after the Treasury announced measures against dozens of Syrian ministers.

“We are working urgently with our international partners to push for a political transition in Syria,” Vietor said.

“The sooner this transition happens, the greater the chance we have of averting a lengthy and bloody sectarian civil war and the better we’ll be able to help Syrians manage a stable transition to democracy.”

The bomb that ripped through a high-level security meeting in the Syrian capital killed top regime officials — including Assad’s brother-in-law.

Syrian state-run TV confirmed the deaths of Defense Minister Dawoud Rajha, a former army general and the most senior government official to be killed in the rebels’ battle to oust Assad; and Gen. Assef Shawkat, the deputy defense minister and one of the most feared figures in Assad’s inner circle. He is married to Assad’s elder sister, Bushra. An authority with direct knowledge of the situation told The Associated Press that Hassan Turkmani, a former defense minister, also was killed.

The bombing was the harshest blow to the government’s inner circle since the uprising began last year. A senior US defense official said Assad’s whereabouts at the time of the bombing were not yet clear. The official, who spoke on condition of anonymity to discuss the administration’s internal deliberations, said it was too soon to say with certainty that the attack was perpetrated or facilitated by Assad insiders, but he said it suggested the possibility of new cracks in the Assad regime.

Hammond and Panetta both stressed the urgency of finding a political solution that requires Assad’s exit.

“It’s extremely important that the international community, working with other countries that have concerns in that area, ... bring maximum pressure on Assad to do what’s right to step down and to allow for that peaceful transition,” Panetta said.

“The violence there has only gotten worse and the loss of lives has only increased,” Panetta said, “which tells us that this is a situation that is rapidly spinning out of control.” He said that is all the more reason for the international community to bring “maximum pressure” on Assad to step down and permit a stable transfer of power.

Hammond suggested that Russia and China hold the key to finding a peaceful solution.
“The regime exists at the moment because it receives tacit support from other powers in the world,” he said. “If those powers are sending clear messages about the limits of their tolerance for the activities of the regime, that will be an effective constraint on the activities of the regime.”

Panetta and Hammond both cautioned the Assad regime not to lose control of its chemical weapons.

“We will not tolerate the use or the proliferation of those chemical weapons,” Hammond said, adding, “So our diplomacy has to focus on getting those who have the greatest influence with the regime to ensure that it acts responsibly in relation to chemical weapons.”