Syrian rebels backed by the United States are making their biggest gains yet south of the capital Damascus, capturing a string of towns from government forces and aiming to carve out a swath of territory leading to the doorstep of President Bashar Assad's seat of power.
The advances appear to be a rare visible success story from efforts by the US and its allies to train and arm moderate rebel fighters.
The rebel forces are believed to include fighters who graduated from a nearly 2-year-old CIA training program based in Syria's southern neighbour Jordan.
The group known as the Friends of Syria, including Jordan, France the US and Saudi Arabia, are backing the rebels with money and weapons, said General Ibrahim Jbawi, the spokesman for the Free Syrian Army's southern front.
The gains are a contrast to northern Syria, where US-backed rebels are collapsing in the face of an assault by Islamic militants.
Notably, in the south, the rebels are working together with fighters from al-Qaida's Syria branch, whose battle-hardened militants have helped them gain the momentum against government forces.
The cooperation points to the difficulty in American efforts to build up "moderate" factions while isolating militants.
"The goal is to reach the capital ... Because there is no way to bring down the regime without reaching Damascus," said Ahmad al-Masalmeh, an opposition activist in Daraa.
But few are under the illusion that the offensive in the south can loosen Assad's grip on power in the near future. The Syrian leader has benefited from the US-led coalition's war against the Islamic State group, which has had the side effect of freeing up Assad's forces to focus on more moderate rebels elsewhere in the country. Government forces have seized several key areas around the capital.
Rebels in the south say they hope the new push will be just enough to pressure Assad to negotiate a peaceful solution to the conflict.
Jbawi said the international support for the assault "is not enough to let the rebels win the battle militarily. They are backing (us) to pressure Bashar Assad's regime to bring him to the negotiating table.
