Wednesday's bombing in Damascus ripped deep into the Syrian regime's inner circle and followed the fourth day of fighting in the streets of the capital.
But the brazen assassination of the country's defence minister and two associates is not, in itself, a game changer, according to those who follow the Mideast conflict closely.
"There’s going to be a tipping point out there as long as this continues," warned U.S. political analyst Christopher Chivvis.
But at this point, he and others say it is too early to forecast the end of President Bashar al-Assad's repressive regime and that much will depend on whether there is a new flurry of defections, particularly among the ruling Alawite population, and what happens in the battle for Damascus, which serves as the regime's power base.
Rebels claimed a huge victory Wednesday after the brazen bomb attack in the Syrian capital. At least three top officials, including Defence Minister Dawoud Rajha, Deputy Defence Minister Gen. Assef Shawkat, who is also Assad's brother-in-law, and former defence minister Hassan Turkmani were killed while participating in a high-level security meeting.
The bombing came on the fourth day of fighting between opposition and government forces in the streets of the capital city and less than a week after the Syrian ambassador to Iraq defected, one of a series of high-profile defections.
But despite these apparent victories by a strengthening opposition in the 17-month uprising, University of Western Ontario professor Peter Fragiskatos cautioned against overstating their significance.
"The opposition tends to ignore the fact that the regime is still very strong," said Fragiskatos, who specializes in conflict and peacebuilding. "It has hundreds of thousands of soldiers and its most elite elements have not defected."
He points out that most of the recent defections from the Syrian army are largely by Sunni Muslims, who form most of the opposition against the Syrian regime, and not by the Alawites, the minority sect that dominates the officer corps and has kept the Assads in power.
"If the Alawite defect en masse, we're in for a change," Fragiskatos says. If that doesn't happen, he adds, the situation will probably stay the same for the foreseeable future.
Roland Paris, founding director of the University of Ottawa's Centre for International Policy Studies, agrees that if we see more defections from inside the regime, indicating an internal collapse, "then that would be a game changer."
Another would be if the opposition made "significant and dramatic gains" in securing territory and defeating the Syrian military.
"In those circumstances, it would signal the possibility that the stalemate that we've seen developing over the past few weeks might be tipping one way."
Until now, Assad's regime has managed to avoid the "trip wires" that Libya's Moammar Gadhafi "stumbled across in March of last year that triggered" an international intervention, says Chivvis, a Washington-based senior political scientist with the non-profit Rand Corporation.
"[Assad] controlled his rhetoric in a way that Gadhafi didn't. He's given the appearance of a willingness to negotiate with Kofi Annan. All of the things that Gadhafi did not do. By doing these things, he's managed to avoid intervention" by the West.
Assassinations, defections and fighting in the capital, however, could render the situation "so potentially chaotic" as to demand international action, Chivvis warns. Though Russia has been loath to sanction any UN action.
"What I see happening is the situation on the ground getting significantly ahead of the international response," said Chivvis, who specializes in military interventions.
Wednesday's brash attack came as the UN Security Council was scheduled to vote on a resolution aimed at slapping Syria with economic sanctions if it did not agree to a peace plan negotiated three months ago. The vote was delayed by a day, but Russia, a close ally of Syria, is expected to veto the resolution in any event.
Beyond the resolution, there have been few "appealing" or "workable options," said Paris.
A number of countries, including Canada and the European Union, a key trading partner, have imposed economic sanctions on Syria. The U.S. is also providing so-called "non-lethal" support, which includes communication devices and medical supplies, to opposition groups taking on the regime.
Reports suggest Saudi Arabia and Qatar are supplying arms and paying salaries to the rebel groups trying to topple Assad.
"What is in place from the international community is a pretty stringent set of sanctions and substantial but still covert support for the opposition groups," said Paris.
But that alone is likely insufficient to end Assad's grip on power and Paris warns that any military incursion into Syria, even for humanitarian purposes, would have to begin with a campaign to destroy the country's powerful air defence — and would likely incur many civilian casualties.
"So if we’re prepared to go to war with the Syrian regime to the bitter end and defeat it, then let's consider military options," he says. "But let’s not fool ourselves into thinking that there are military options that don't involve a war with the Syrian government."
For now, though, Fragiskatos predicts the international community will continue "pursuing humanitarian intervention on the cheap," which includes getting arms and funds to opposition groups from external sources.
Some experts, however, believe a formal intervention is just a matter of time.
"All these things are now adding up," says Chivvis. "And eventually some kind of action will be necessary."