In what appears to be the most successful and audacious attack by the rebel movement in Syria yet, an explosion in Damascus on Wednesday killed at least two members of the regime’s inner circle.

Exactly who carried out the attack or whether the explosion involved a suicide bomber is not known. What is certain is that President Bashar al-Assad’s brother in law General Assef Shawkat and defense minister Dawoud Rajiha were killed. Spokesmen for the rebel Free Syrian Army are rejoicing at the news, claiming responsibility for the operation.

Until today, Assad’s core supporters in the Syrian security establishment were insulated from the violence that has swept across the country since early last year.

Among the dead are the very men who have implemented Assad’s counterinsurgency strategy. The death of Assef Shawkat, who served as deputy defense minister, is seen as an especially harsh blow to the president’s fortunes. Shawkat has been a regime insider since he married the president’s sister in the 1990s, serving in high level positions ever since. Syrians both in- and outside of the country have long considered him to be the third most powerful man in the government, behind the president and his younger brother Maher.

The scope of the attack in the very heart of the government’s center of gravity suggests that the regime is starting to lose the type of cohesiveness and internal strength that has sheltered Assad since the conflict began. The fact that a bomb was able to detonate during a meeting of Syria’s most important security chiefs, let alone kill several of those officials, is a profound demonstration of the rebel movement’s resilience on the ground as well as its complete loss of faith in the international community.

In addition to the killing of Shawkat and General Rajiha, interior minister Mohammad Ibrahim al-Shaar and Syria’s intelligence chief Hisham Bakhtiar were wounded in the attack. 

All eyes will now turn to Bashar al-Assad where the temptation for a forceful response is likely to outweigh any considerations of saving himself and his family by leaving Syria in exile.

The Syrian government’s official news service released a statement promising that the regime will not waver in the face of what it has long described as acts of terrorism supported by Arab Gulf states, Al Qaeda, Israel and the United States.

With such a debilitating loss of personnel, Assad will likely be forced to use even more violence to rout the latest territorial gains that have been made by the Free Syrian Army. Anything other than a show of force against rebel positions will be viewed by the rebel leadership as weakness and a sign that more high-profile assassinations may drive Assad from the capital.