Syrian rebels have stepped up their siege of a government helicopter base and clashed with soldiers near Aleppo's international airport, part of an effort to chip away at the air power that poses the biggest challenge to their advances against the regime of President Bashar Assad.
That airborne threat came into stark relief the same day, when a government air strike on a northern town killed 14 people - most of them women and children, activists said. More than 21-months into Syria's conflict, the Assad regime is counting more than ever on its air force to block rebel gains.
Rebels in the north, a region largely clear of government troops, realise this and have launched campaigns to seize all the area's airports, hoping such a move will protect their forces and the civilians who back them.
Rebels say they have surrounded four airports in the northern province of Aleppo. In recent days, they have posted dozens of videos online showing fighters shooting mortars, homemade rockets and sniper rifles at targets inside the bases.
It remains unclear whether rebels will be able to seize any of the bases soon, but they have managed to stop air traffic at one and limit movement at others by firing on all approaching aircraft with heavy machine guns.
"The airports are now considered the most important thing the rebels can focus on because all of the strikes now come from the air," said Aleppo activist Mohammed Saeed via Skype.
Saeed said clashes between rebels and government soldiers raged until this morning around the Mannagh helicopter base near the Turkish border. He said other rebel groups continued to hold positions around the Kuwiras military airport south-west of the city of Aleppo and clashed with soldiers near Aleppo's international airport and neighbouring Nerab military airport.
Rebels have numerical superiority and support from most of the population in the far north, making it easy for them to surround and cut the ground supply lines to government military bases.
But Assad's forces still control the air, responding to rebel gains with airstrikes on their positions or residential areas, a tactic rebels consider collective punishment against civilians who back the revolt.
The rebels remain largely helpless against regime airpower, and credible reports of them shooting down government aircraft are rare. But many groups now have heavy calibre anti-aircraft guns they say act as a deterrent to low-flying aircraft.