The killing of high-ranking regime officials this month, followed by high-level defections, indicates that the Syrian regime is coming under increasing pressure from within, analysts said.

The Syrian regime suffered a significant setback last week after opposition fighters struck a major blow to the regime in a bomb attack in Damascus on Wednesday (July 18th), followed by military advances in Damascus and Aleppo.

The Free Syrian Army (FSA) took control of one Iraqi border gate and three on the Turkish border, including Bab al-Hawa across from the Cilvegozu gate in Hatay. Regime troops battled FSA fighters in Aleppo and in several Damascus neighbourhoods.

On Sunday, the Arab League stepped up pressure, calling on Syrian President Bashar al-Assad to step down and urging the FSA to form a transitional national unity government.

The bombing of the National Security headquarters killed Assef Shawkat, Assad's brother-in-law and deputy defence minister; Defence Minister Dawoud Rajha; General Hassan Turkmani, head of the regime's crisis cell and assistant to the vice president; and national security chief Hisham Ikhtiar. Interior Minister Mohammed al-Shaar was wounded.

High level defections

The attack follows a wave of recent high-level defections, including a senior Republican Guard commander and Syria's ambassadors to Iraq and the UAE.

"Mass bombings … will surely bring more defections and mistrust, as they create shocks for the ruling al-Assad family," Salih Akyurek, a retired Turkish colonel and security analyst at the Wise Men Center for Strategic Studies in Ankara, told SES Türkiye.

Turkey and the Syrian side of the border have become home to thousands of opposition fighters, composed of defected soldiers and civilians, who have taken control of large pockets of territory inside Syria. More than 100 high-level military officials have defected to Turkey, including 24 generals, according to the media. More than 43,000 Syrians are living in Turkish refugee camps.

The military in Syria is a critical institution of the state, and senior military officers who are risking their lives by defecting will want to be part of the new system, analysts said.

"The generals don't simply leave al-Assad for a cozy life. They want to stand with the [opposition] and be at the centre of the struggle. They see Turkey as a real centre of the Syrian uprising," Veysel Ayhan, chairman of the Ankara-based International Middle East Peace Research Centre, said.

Before defecting, officers co-ordinate with the army and the Syrian National Council, "who help them smuggle their families across the border to Turkey", said Edward Dark, an Aleppo-based Syrian activist and editor of the website Syrialeaks.

"These defections are significant because they show that the regime can no longer rely on the army to repress the population, more and more officers are refusing to carry out orders, and plan to defect," Dark said. "The defectors still have influence and contacts back home in the regime army, as well as helping the FSA with experience, advice and command."

One indicator of the stress facing Assad's inner circle, according to these analysts, is the recent defection of General Manag Tlass, a commander of a Revolutionary Guard unit and son of former Defence Minister Mustafa Tlass, who after escaping to Turkey has surfaced in Paris.