[1] Shawkat was a key suspect in a terrorist attack in Beirut that killed Lebanese Prime Minister Rafic Hariri on 14 February 2005.

In 1983, after Hafez al-Assad suffered an apparent heart attack, he named governing council of six men he believed were unlikely to seize power to run the country in his absence.

His portfolio included liaising with militant Palestinian groups, such as Hamas and Islamic Jihad, and he was a key architect of Syria's dominance of Lebanon.

[12] Shortly before his promotion, former Lebanese Prime Minister Rafik Hariri was assassinated by a car bomb in Beirut on 14 February 2005.

The size and sophistication of the device used in the blast was considered to have involved a state intelligence agency, and United Nations investigators implicated Shawkat in the plot.

[13] He was subsequently administratively detained, and in July 2009, he was dismissed as head of military intelligence, 'thus ridding the regime of the key suspect in the international investigation into Hariri's assassination', given the rank of general and named as deputy chief of staff of the armed forces.

[1] He was a member of a military crisis unit created by President al-Assad, which included Defense Minister Dawoud Rajiha, intelligence chief Hisham Bekhityar, special security advisor Ali Mamlouk, head of military intelligence Abdel-Fatah Qudsiyeh, and Mohammed Nasif Kheirbek, a veteran operator from the era of Assad's father.

In May 2012, the Free Syrian Army's (FSA) Damascus council claimed that one of their operatives from its Al Sahabeh battalion had poisoned the eight members of Bashar Assad's military crisis unit, including Assef Shawkat, who was inaccurately reported to have died.

[18][19] On 18 July 2012, Shawkat attended a meeting of the Central Crisis Management Cell (CCMC) at the headquarters of Syria's national security council in the Rawda Square of Damascus.

[17] As'ad AbuKhalil, a California State University professor, argues that Shawkat was the key man in the group assassinated.