The rebel Free Syrian Army has grown from a rag-tag force into a popular guerrilla insurgency buoyed by civilian fighters who still lack weapons and structure to defeat the regime, experts and rebels say.
Over the past months more and more civilians have volunteered to take up arms alongside army deserters against the regime of Syrian President Bashar al-Assad, as deadly violence escalates across the country.
"The Syrian army has one million men in reserve, civilians with military training, and many of them are joining the revolt now," said Riad Kahwaji, who heads the Institute for Near East and Gulf Military Analysis (INEGMA).
According to the Dubai-based Kahwaji, the FSA has "thousands" of members across Syria and is growing in both capacity and coordination. "They have become more organised," he told AFP.
The FSA announced in March the formation of a military council grouping rebel chiefs and chaired by Syria's most senior army deserter, General Mustafa al-Sheikh.
While Turkey-based Colonel Riad al-Assaad, one of the first officers to defect, officially leads the FSA, in practice operations are planned and executed at a grassroots level, independently from any exiled leaders, Kahwaji said.
Over the past months more efforts has been made to shore up the rag-tag rebel army into a more cohesive force, activists say.
"Small groups of armed rebels with no communication with other units are being replaced by larger umbrella squadrons to better organise the insurgency," said Damascus-based activist Ahmad al-Khatib.
Thus fighters from key rebel bastions have been grouped together under one commander each, added Khatib, who participates in efforts to unite the FSA and encourage defections.
"There is no unified leadership, but now units in different parts of Syria are communicating with each other," he told AFP via Skype.
"The more coordinated the FSA, the more effective it becomes, and the better the support its fighters are given by civilian opponents to the regime."
For Kahwaji the FSA is a "popular army, which enjoys the increasingly broad support of the Syrian population."
But he admitted that the rebel fighters are ill-equipped with only medium and light weapons that are no match for the firepower, tanks and helicopters available to the Syrian army.
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"The FSA fighters are not well armed, but the population feeds them and gives them cover," he said. The rebels are "operating in a hospitable environment" unlike the regular army which is faced with "hostility."
Support from the civilian population may help keep morale up for the rebels but they, too, recognise their shortcomings.
"Every day of resistance is a success, but Assad's army remains superior," said Nasser Nahhar, a rebel unit commander operating around the restive Baba Amr neighbourhood of the flashpoint central city of Homs.
"The Syrian army has tanks and helicopters, whereas we have light weapons. If it weren't for that, we would have won already," he told AFP via Skype.
According to Nahhar, what begun as a peaceful uprising against a ruthless dictatorship turned into an armed struggle with "the majority of anti-regime fighters now being civilians."
"We wanted to take down the regime peacefully, but it was impossible," said the well-spoken civilian-turned-rebel commander in his late 20s. "The only way to defeat the regime now is militarily."
As deadly violence escalates across Syria, the FSA has opted for new tactics drawing from a history of guerrilla warfare to make up for its equipment shortcomings.
"The FSA's main goal right how is to try and harass the army to the point of fatigue," said Elias Hanna, a Lebanese ex-military officer and professor of geopolitics at the American University of Beirut.
"The more we exhaust the regular troops, the more we weaken their morale and force defections," he added.
But Hanna warned that the rebels "cannot go on like this much longer" and described them "an army on the run."
"Without a clear regional decision to provide the FSA with the means it needs to continue fighting -- such as safe routes and a base -- the rebels cannot take fighting onto the next level," Hanna said.
Energy-rich Arab nations like Qatar and Saudi Arabia have repeatedly called for arming the Syrian rebels but Western powers are still resisting any military intervention in the 16-month crisis.
And while the rebels initially hoped for a speedy intervention, Nahhar explained that the prime choice now is to rely on hit-and-run tactics. "We don't need to win, we just need the army to lose," he said.