I suggest that the answer is yes, inasmuch as that they are being actively used against a defenceless civilian population.
Thats a moral objection, and you and I may or may not agree with it. But the facts of the matter is, in all out war the civilians are part of the strategic equation whether we like it or not.
Our compliance to such things has been patchy, depending on the circumstances and the risk reward ratio, hence condemning Assad is rather hypocritical of the west.
Governments have a moral and humanitarian responsibility to minimise damage to property and death of civilians, regardless of whether they're a member of the UN.
Governments have no responsibility what so ever for that, its a moral view point depending upon where you stand. Maybe the moral responsibility should be to do what ever it takes to end the situation as quickly as possible.
Whats worse, x amount of people killed brutally in a short amount of time, or 10x over a longer amount of time.
If Russia pulls the gloves off, it may be able to help. The strategy we are doing now is deeply flawed and hamstrung by politics.
Think about whats happening and the time constraint we are under!
The situation has been going on for over an year now, whats the birth rate, whats the indoctrination level in those areas. The fact is, children are being indoctrinated every day, females are probably being forced to spit out children like vending machines.
Even if we kill off the leadership, whats left behind will be a deeply indoctrinated population. Effectively we will have changed the mean level of extremism in the population,
Another words the potential for this to grow exponentially is a real possibility. At the end of the day, we need to be killing ISIS supporters etc in their thousands every day or weekly.