(CNN) -- After significant losses to rebels in the northern province of Idlib, Syrian government forces have launched a counteroffensive using airstrikes, helicopters and heavy artillery, according to opposition activists. One of their objectives is to retake control of the main highway linking Damascus and Homs with the cities of Aleppo and Idlib in the north.
Dozens of videos uploaded from the province in recent days, as well as reports from opposition activists, indicate a growing use of air power by the regime of Bashar al-Assad as it tries to reclaim control of the vital north-south artery.
At the same time, they suggest rebel units are increasingly able to launch coordinated attacks against military bases and outposts. Opposition activists claim that hundreds of soldiers are now trapped in two bases in northern Syria.
Last week, rebels belonging to the Sukour al-Sham brigade, one of the strongest in northern Syria, launched a multipronged attack on military outposts around the strategic town of Maarat al-Numan, which is adjacent to the main highway. After two days of fierce fighting, government forces retreated.
It remains difficult to develop an accurate picture of the fighting in Idlib in the absence of independent reporting. But videos posted over the past few days provide a snapshot of the regime's counteroffensive.
They include the aftermath of bombings in Maarat al-Numan and surrounding villages. In one, posted Wednesday, rescuers scrambled through clouds of dust to search the rubble of a large building looking for survivors.
Other videos posted Tuesday showed bombing raids and the collapse of one building of at least four stories. Footage Monday showed rebel forces using anti-aircraft and heavy machine guns hidden in olive groves to try to bring down helicopters and fighter jets, apparently unsuccessfully. But according to a video that surfaced Wednesday, rebels were successful in bringing down a military helicopter near the city of Idlib.
A correspondent for the French news agency AFP who was in Maarat al-Numan earlier this week reported intense airstrikes. Herve Bar wrote of a man cut to pieces in one air raid, with what remained of him collected into heavy plastic bags.
"My son is in a plastic bag," the man's mother cried, according to Bar's report. "I want to see his face one last time."
The town itself is now said to be largely deserted, after people fled for fear of the inevitable counterattack.
Other videos uploaded purportedly show aerial attacks on villages either side of the main highway and around an important military base at Wadi Aldaif. Opposition activists claim the base -- about two miles from Maarat al-Numan -- has been surrounded for a week.
According to Abu Abdel Rahman, an opposition activist in Idlib, a large number of soldiers and heavy weapons are trapped at the base with few resources. At one point, he told CNN, a regime plane dropped sacks outside the base. Rebel units found food rations and other supplies in the sacks. Rahman said Free Syrian Army commanders were negotiating via radio with the military for the surrender of the base.
Some 40 kilometers (25 miles) to the northwest of Maaret al-Numan, other rebel units claimed last week to have captured more than 250 Syrian soldiers and militia close to the town of Jisr al-Shugur, near the border with Turkey.
Activist Tariq Abdul-Haqq told CNN that rebels had taken control of three villages in the area. He said seven units participated in the attacks. Videos subsequently uploaded purportedly show dozens of captured soldiers and pro-government militia sitting in what appears to be a warehouse near the town of Jisr al-Shugur. Some of the captives were in uniform; many were not.
Driving government forces out of this area would improve the rebels' access to the nearby Turkish border and their ability to bring in supplies and weaponry.
Human Rights Watch says the regime has resorted to using cluster munitions in Idlib and elsewhere, pointing to a number of videos posted in recent days showing Russian-made cluster bombs.
"Human Rights Watch has confirmed that the remnants shown in the videos are RBK-250 series cluster bomb canisters and AO-1SCh fragmentation bomblets," the group said Monday. Each RBK-250 is designed to carry 150 such bomblets. A video posted by an opposition group Tuesday -- purportedly from Idlib -- clearly shows the markings of an RBK-250. The Syrian military has denied using cluster munitions.
Although it is difficult to piece together a broad picture of the latest fighting in Idlib, there does seem to be a growing capability among some rebel brigades to plan and carry out coordinated attacks, even though they remain substantially outgunned.
At the same time, the regime appears to have stepped up its use of air power as the situation on the ground has become more tenuous.
For both sides, the stakes are high.
While rebel brigades have held rural areas for months, they have not been able to threaten the regime's control of major conurbations. But if the regime is unable to keep supply lines open between Damascus and northern Syria, its forces in Aleppo and Idlib may become more isolated.
Amir Ahmed and Yousuf Basil contributed to this report