With foreign aid and training of rebels in Jordan ramping up, the opposition fighters have regained momentum in their fight to topple President Bashar Assad.
But while the fall of southern Syria would facilitate the rebel push for Damascus, it might also create dangerous complications, potentially drawing Syria's neighbors into the 2-year-old civil war. Besides abutting Jordan, the region includes territory that borders Syria's side of the Golan Heights, along a sensitive frontier with Israel.
"This is a very sensitive triangle we are talking about," said Hisham Jaber, a retired Lebanese army general who heads the Middle East Center for Studies and Political Research in Beirut. "The fall of Daraa, if it happens, may usher in strategic changes in the area."
For the rebels, control of the south is key to their advance toward Damascus. Dozens of fighting brigades have carved up footholds in areas to the east and south of the capital, where they fire off mortar shells on the heavily guarded city.
The significance of their gains in the south was on display Wednesday when the rebels stormed a military base after a five-day siege.
"Damascus will be liberated from here, from Daraa, from the south," declared an armed fighter, a rifle slung over his shoulder and a kaffiyeh tied around his face. Videos posted online by activists showed him and other unidentified rebels celebrating inside the Syrian army's 49th battalion in the village of Alma, on the outskirts of Daraa.
"We will march to the presidential palace from here," said another fighter, amid bursts of Allahu Akbar, or God is great. The videos showed rebels from the Suqour Houran, or Eagles of Houran brigade, driving a Russian-made armored personnel carrier inside the base. "These missiles are now under our control," said a fighter, standing before a missile loaded on a truck.
Another video, posted by the Fajr al-Islam brigade, showed the rebels walking around the base as the heavy thud of incoming artillery rounds fired by nearby regime forces was heard in the background. A destroyed rocket, army trucks and radars were seen on the ground.
The videos appeared consistent with Associated Press reporting from the area.
The capture of the base is the latest advance by opposition fighters near the strategic border with Jordan. Last month, opposition fighters seized Dael, one of the province's bigger towns, and overran another air defense base in the region.
Opposition fighters battling Assad's troops have been chipping away at the regime's hold on the southern part of the country in recent weeks with the help of an influx of foreign-funded weapons.
Their aim is to secure a corridor from the Jordanian border to Damascus in preparation for an eventual assault on the capital. And they have made major progress along the way. Activists say several towns and villages along the Daraa-Damascus route are now in rebel hands.
A Western diplomat who monitors Syria from his base in Jordan said the fall of Daraa appeared imminent, possibly in the next few days or weeks. His assessment was based on classified intelligence information, he said, speaking on condition of anonymity in order not to hamper his intelligence-gathering efforts.
Daraa's fall could unleash lawlessness on Jordan's northern border and send jitters across the kingdom, a key U.S. ally which fears Islamic extremist groups on its doorstep.
Also of grave concern are rebel advances in areas near the Israeli-occupied Golan Heights.
"If Daraa falls, the rebels will come face-to-face with the Israeli army in the Golan," said Hilal Khashan, a political science professor at the American University of Beirut.
Daraa province separates Damascus from the Golan Heights, which Israel captured in 1967 and annexed in 1981. In recent weeks, Israel has seen Syrian mortar rounds and bullets land in Israeli territory and tanks enter a demilitarized zone in the Golan Heights. Israeli security officials believe the incidents have been inadvertent but have threatened to retaliate.
In addition to complications arising from rebels controlling the frontiers with Israel and Jordan, the fall of Daraa may drag in members of Syria's minority Druse community who live in the southern province of Sweida, Khashan said.
Like other minorities in Syria, they have so far remained largely on the sidelines of the uprising, but that could change if they feel threatened by the Islamic rebels.
The series of rebel gains coincided with what regional officials and military experts say is a sharp increase in weapons shipments to opposition fighters by Arab governments, in coordination with the U.S., in the hopes of readying a push into Damascus.
Thousands of fighters have entered Daraa in recent weeks, said Jaber, adding that rebels capitalizing on new weapons aim to use Daraa as a launch pad for reaching Damascus. Still, he and other analysts said the fall of Daraa would not change the balance of power unless the rebels acquire more advanced weapons.
More importantly, the rebels would also need to cut off the roads linking Damascus to the central province of Homs and from there to the Syrian coast.
Many observers believe Assad, as a last resort, would carve out a breakaway enclave for himself and his fellow Alawites in their historic heartland in towns and villages of Syria's mountainous coast, from which they would fight for survival against the Sunni majority battling to topple him.
The Syrian revolt started with peaceful protests but turned into a bloody conflict after some Syrians took up arms to fight a brutal government crackdown on dissent. The fighting has taken increasingly sectarian overtones, with Sunni Muslims dominating the rebel ranks. The Assad regime is dominated by Alawites, an offshoot Shiite group to which the president and his family belong.
The uprising began from Daraa, a largely agricultural region predominantly populated by Sunnis, in March 2011. Although long considered a regime stronghold, small protests began calling for the release of teenagers after they were arrested for scrawling anti-regime graffiti on the walls.
The conflict has turned into a civil war that the U.N. says has killed more than 70,000 people.
The rebels control vast portions of northern Syria bordering Turkey. They've also captured areas in the east along the border with Iraq recently, but the strategic region between the southern outskirts of Damascus and Jordan—known as the Houran plains—is seen as a crucial gateway to the capital.
Both sides consider Damascus, about 60 miles (100 kilometers) from the Jordanian border, the ultimate prize.
Millions of Syrians have fled the conflict, seeking refuge in neighboring Jordan, Lebanon, Iraq and Turkey, raising fears the civil war could spread across the region as the fighting occasionally spills over Syria's volatile borders.
In Lebanon, a Syrian jet fired a missile that slammed into a house on the outskirts of the border town of Arsal, causing material damage but no casualties, according to Lebanese state media. The Sunni Muslim town has backed opposition fighters in Syria, and arms smuggling is widespread in the area.
Lebanese gunmen supporting opposing sides of the conflict have frequently clashed, raising concerns the fighting could re-ignite Lebanon's explosive sectarian mix.
Associated Press writers Jamal Halaby in Amman, Bassem Mroue and Barbara Surk in Beirut and Suzan Fraser in Ankara, Turkey, contributed to this report.