A Free Syrian Army fighter aims his weapon as he takes up a position behind sandbags in the al-Khalidiya neighborhood of Aleppo on Aug. 4. (REUTERS)

Syrian rebels claimed Tuesday that they captured a long-contested military air base near the northern city of Aleppo and advanced in the loyalist heartland of Latakia, capping a day of setbacks for the government that underscored the see-saw nature of the Syrian civil war.

Rebels overran the Menagh air base after carrying out a suicide bombing Monday near its main building, which had become a last refuge for government troops penned inside the compound, opposition activists said. In videos posted online, rebels showed off their spoils of ammunition and weapons.

Although President Bashar al-Assad’s forces have gained ground in central Syria, the reported capture of Menagh indicated the strength of rebel forces in the north, where they control swaths of territory with direct supply routes from Turkey.

Opposition forces, led by hard-line Islamist factions, have also pushed forward in the northwestern province of Latakia, where they claim to control a string of Alawite villages after killing hundreds of government loyalists over a three-day offensive and sending droves of residents fleeing.

The rebel advances deal a blow to Assad’s government, which has been trumpeting its progress in the central city of Homs, once an opposition stronghold, and in the suburbs of the capital, Damascus.

But though the gains might reassure Assad’s international opponents after concerns that the rebels was losing on the battlefield, they are also likely to spur concerns about the jihadist groups leading the charge.

The al-Qaeda-linked Islamic State of Iraq and the Levant played a major role in the assault on Menagh and the gains in Latakia, opposition groups said.

If the fall of the air base holds, it would free up rebel fighters for other fronts, including Aleppo itself, analysts said.

“The seizure of [Menagh] will likely prove a turning point within the wider Aleppo and northwest theaters,” said Charles Lister, an analyst for IHS Jane’s Terrorism and Insurgency Center.

Another of those fronts is in Latakia, where rebel advances are particularly symbolic, as the province is the heartland of the Alawite sect, an offshoot of Shiite Islam to which Assad belongs. Rebel fighters claim to be within striking distance of the ruling family’s home town, Qardaha.

Mohammed Faizou, a Latakia-based rebel, said opposition forces killed 300 government troops and members of the pro-Assad shabiha militia. Other rebels put the death toll somewhat lower.

“The objective is to reach Qardaha and hurt them like they are hurting us,” said Ahmad Abdel­qader, an activist with the rebels’ Ahrar al-Jabal Brigade, the Reuters news agency reported. “The Alawites have been huddling in their mountain thinking that they can destroy Syria and remain immune.”

Later Tuesday, rebels demonstrated their ability to continue to strike near Assad’s seat of power, as a car bomb killed 10 people and wounded 56 in the Damascus district of Jaramana, according to state television. The neighborhood is home to a large population of Christian and Druze minorities, seen by many observers as more sympathetic to the government than the majority Sunni Muslims.

The isolated Menagh air base — surrounded by open land, which makes an assault logistically challenging — was one of a few remaining pockets of government control in the countryside north of Aleppo, which rebel and government forces have been battling to control since July 2012.

The base, used for launching airstrikes on the surrounding territory, had been under siege for months.

The assault Monday was spearheaded by two suicide bombers from the Islamic State, both non-Syrians, who detonated their explosives inside a Soviet-made BMP military vehicle near Menagh’s main building, according to Aleppo activist Kareeb Adeeb and the Britain-based Syrian Observatory for Human Rights. The assault was also assisted by a defecting officer who killed the base’s commander, Adeeb said.

The more-moderate Northern Storm Brigade, which also played a major role in the offensive, according to activists, released a video statement Tuesday declaring that the opposition had gained control of the airport. “It’s true it came late, but still, it’s a victory,” one rebel said outside the main gates.

The opposition-run Aleppo Media Center said that rebels seized 10 tanks in the operation and that the base was “completely liberated.” However, the state-run Syrian Arab News Agency denied that any military equipment or aircraft were left at the base, which it described as “not in service.” It said that rebels were suffering “very severe losses” in and around the airport and that its guards were “fine.”

“The heroes of our armed forces are confronting the terrorists with matchless valor,” the agency said.

Suzan Haidamous and Ahmed Ramadan contributed to this report.