In a military conflict, combat and collateral damage, included that from bombs, rockets, IEDs, booby traps, rifles, pistols, and poison gas or water, kills or injures people. And NOBODY (arguably, not even children, especially those able to wield a weapon, because parents are responsible for them) are innocent.
So, let us take the point of collateral damage or slaughter of the arguably innocent. If that worries heads of state and their war theorists, then they shouldn't wage war because collateral damage is unavoidable, and in fact it is often necessary in order to force an adversary to sue for peace.
Given that heads of state don't intervene or stop the conflict at its outset by such overwhelming and irresistible force as to defeat combatants immediately, they are all in a measure responsible for collateral damage, and they should just shut up and stop whining about it.
Looking at the videos of the sick and dying from the chemical attack in Khan Sheikhoun, Syria, and comparing that to the clouds of smoke and ash from today's high explosive bombing that killed people in the same area, I have to wonder if Trump is loony for wasting US money on his moralizing tomahawk missile attack on the Sha'irat Syria air base the other night. His attack proved nothing other than the inability to think straight and willingness to piss away taxpayer money in pique.
The USA needs to get its military out of the Mideast and Central Asia altogether, and precede any future interference with tactical nukes to take out the chief troublemakers.
And Americans should take note of the anti-American treachery of the Obama administration in funding and arming the Syrian rebels in a Qatar/Saudi conspiracy to force Assad to allow a Qatar gas pipeline to run through Syria. Obama might have intended the scheme to let Qatar gas compete against Russian gas in Europe, and as a consequence to collapse Russia's economy as punishment for invading Ukraine and Georgia and snatching the Crimean peninsula. How is that in US interest? It isn't. If Ukraine, Moldova, and other former Soviet possessions want protection, they should pay their share and join NATO.
Obama's stupid scheme has cut loose 5 million Syrians, including many terrorists among them, not to mention countless Iraqis and Afghans, to migrate elsewhere as refugees to set up Islami states wherever they go. I personally do not welcome the Muslims and stupid among them into the USA, nor should anyone else of good sense.