Unlike the more staid Assad, the flamboyant 48-year-old Hassan has often boasted of his efforts to exterminate regime enemies. This has endeared him to loyalists—and, it seems, to Vladimir Putin, the president of Russia. As he delivered his sermon of fire and fury that day on the edge of Ghouta, next to him stood four mysterious-looking soldiers dressed in full combat gear and masks. They appeared to be part of a personal security detail provided by the Russians.

True to Hassan’s words, Syrian government forces and their Russian backers unleashed hell on eastern Ghouta shortly after he spoke. Spokespeople for the Russian military in Syria disseminated a stream of messages via official social media accounts identifying Hassan, commander of the so-called “Tiger Forces,” as the leader of the land troops closing in on the area. The messages said that Russia was backing Hassan and his men with airstrikes and Russian-supplied T-90 tanks, BM-30 Smerch multiple rocket launchers (considered to be among the deadliest in the world) and Tochka ballistic missiles. “We will provide the necessary air support to the forces of Brigadier General Suheil al-Hassan … We have real confidence in their ability to accomplish the mission,” Alexander Ivanov, the spokesman for Russian forces headquartered at the Hmeimim airbase in western Syrian, wrote on the base’s official Facebook page. Later, a pro-Syrian regime website also reported that several Russian army officers were on the ground working with Hassan in a command center in eastern Ghouta.

Since the Russian-backed campaign to retake eastern Ghouta began on February 18, it has killed at least 600 civilians, of whom at least 100 were children. Several thousand people have been wounded. Last weekend, the United Nations Security Council passed a resolution calling for a 30-day ceasefire across Syria. The ceasefire, negotiated on Moscow’s terms, excluded groups that Putin and Assad regarded as terrorists—anyone who has taken up arms to fight the regime. On Monday, Putin ordered a daily five-hour “humanitarian pause” in eastern Ghouta rather than an outright 30-day halt to fighting.

But Russia’s contribution to the destruction in eastern Ghouta has extended beyond providing overwhelming firepower and dictating the terms of surrender. The relentless assault has further revealed Russia’s instrumental role in supporting and promoting Hassan, one of Syria’s most notorious warlords.

On several occasions, the Russian military has acknowledged training and equipping what it has called “detachments” operating under Hassan’s command. These groups, like the Tiger Forces and the 4th and 5th Volunteer Assault Corps, are effectively paramilitary groups attached to regime forces. There are also reports that Russia pays the salaries of these Syrian militia-like formations. Still, Russia has pointed to its support for Hassan and his forces to make two claims: That the Russian army and its local partners defeated the Islamic State in Syria, and that Russian forces, unlike the U.S. military and others, are working with Syria’s legitimate government troops rather than militias or mercenaries.