No doubt the use of barrel bombs is a desperate measure as this weapon is indiscriminate due to it being unguided. But barrel bombs are very probably not a weapon of free choice for the Syrian army. Would the Syrian airforce possess precision „hellfire“ missiles or other smart weapons or would it have defensive weapons that deflect heat seeking anti-aircraft missiles barrel bombs would not have become a military necessity.

To claim that the airforce deliberately uses barrel bombs in order to inflict intentional and maximum civilian casualties is nonsense. Up until July 2012 the Syrian airforce almost played no role. Fixed-wing aircraft entered the civil war after the rebels intrusion into Aleppo and even then often at the rate of dropping 1-2 bombs from Czech L-39 trainer jets.

While the Syrian army implicitly is condoning collateral damage in the shape of civilian casualties its primary target for barrel bombs are rebels fighting from and hiding in civilian neighborhoods. Dozens of rebel video clips clearly show them launching rockets and firing mortars from the middle of civilian areas. Anti-aircraft guns have often been stationed in streets running between peoples houses. Army tanks have been hit by IEDs placed on such streets and convoys have been ambushed on alleyways passing through ordinary neighborhoods.
This is not meant to justify civilian casualties and downplay the devastating effects of inaccurate weapons but it is fair to make clear that many of areas subjected to Syrian army attacks have long lost their „civilian innocence“. Also, especially in vast parts of Aleppo city rebels have chased away the rightful civilian owners and taken away their houses, subsequently turning them into sniper and RPG positions.

In conclusion one could argue that the barrel bomb is a military necessity due to the lack of better weapons.
In contrast many of the violent actions of the rebels are neither accidental nor a „military necessity“.
It is not necessary to:
– mass execute captured and handcuffed prisoners of war
– throw down postal workers from rooftops
– behead disarmed opponents (and accompany a sectarian crime with religious slogans)- send suicide bombers to blow up school children (and later call them „Shabiha kids“)
– detonate water and gas pipelines
– blast electricity plants
– misuse mosques as weapons depots and firing places
– blow up and desecrate mosques and churches of minorities
– intentionally target and kill journalists and reporters critical of the „rebellion“ (and celebrate this on social media)

All these acts have been carried out by all rebel factions, not only the notorious ISIS and al-Nusra. Besides the „others“ who are hardly less sectarian have either closely and regularly cooperated with al-Nusra or openly voiced support and sympathy for them. Thus it is a mystery where and who the „moderate“ rebels are supposed to be and how anyone can seriously claim that it is safe to supply them with more and better weapons because they are „reliable“ and won´t cooperate with the Jihadists or pass their weapons over to them.