Human Rights Watch statement on possible Syria intervention and "the rules of war".
“Military action carried out in the name of upholding a basic humanitarian norm – you don’t gas children in their sleep – will be judged by its effect in protecting all Syrian civilians from further unlawful attacks, whether chemical or conventional,” said Kenneth Roth, executive director of Human Rights Watch.
If there is a military intervention, all warring parties must strictly adhere to the laws of war. The laws of war forbid deliberate attacks against civilians, attacks that do not discriminate between civilians and combatants, and attacks that cause disproportionate harm to civilians compared to the expected military gain. No prohibited weapons should be used, such as cluster munitions, antipersonnel land mines or chemical/biological/nuclear weapons. The parties must take all feasible precautions to minimize harm to civilians and ensure that civilians are not the objects of attack, and avoid deploying forces in densely populated areas.
Parties taking military action should take into account the additional humanitarian needs created by the action, and comprehensively plan and provide for those needs. Given the inadequacy of relief aid provided solely with the permission of the Syrian government, efforts to provide cross-border assistance should be scaled-up dramatically, regardless of Syria’s consent. All parties to the conflict must allow humanitarian assistance to reach civilian populations at risk.
For more than two years, the United Nations Security Council has been paralyzed on Syria and unable to help curtail atrocities because of the repeated vetoes of Russia and China. Quite apart from any military intervention, the Security Council should refer the situation in Syria to the International Criminal Court so that those implicated in serious violations of international law can be appropriately prosecuted, and should implement targeted sanctions against such individuals.
http://www.hrw.org/news/2013/08/28/statement-possible-intervention-syria
These rules should apply to all sides in the conflict. It is clear that HRW intends for that to be the case.