A war crime is committed by an evil regime. That does not justify other nations to commit further war crimes in response. Not even well-intended nations. Not even the United States.
Syrian President Assad's atrocious use of chemical weapons, a war crime under international law, does not justify a military strike by the United States against a sovereign nation. Syria has not attacked the United States. Syria does not threaten the United States. Syria has not attacked or threatened any ally of the United States. An attack by the United States against Syria is therefore not justified, morally or legally.
There are rules of conduct that civilized nations must follow, if they are in fact civilized. One of the most important of those rules is that you do not start wars. You do not attack nations that have not attacked you or one of your allies. A violation of this norm is considered a "crime of aggression" under international law. George W. Bush violated that principle when the US invaded Iraq. We have paid, and continue to pay, a huge price for that arrogant, immoral, and illegal act. Obama, despite his opposition to the Iraq War, is about to commit a similar mistake.
You do not get a free pass to bomb a country because you are disgusted. You do not get a free pass to bomb a country because you painted yourself into a corner with macho rhetoric about bright red lines. You do not get a free pass to bomb a country because you feel impotent in the face of a bloody civil war.
So does Assad get to kill his people with impunity, by any devious means he possesses? No, the world must act to stop him, but it must do so within the framework of international law. If Russia and China continue to block United Nations Security Council action, a coalition of nations must intervene in Syria to support the rebels in view of the crimes committed by Assad. He should then be brought before the International Criminal Court to answer for his actions.
Unfortunately, neither the United States, nor Russia, nor China nor Syria has ratified the Rome Statute establishing the International Criminal Court, though all of them have signed it. Obama could argue that, although he would love to go that route, it is not available to him because President George W. Bush communicated to the UN Secretary-General that the U.S. did not intend to become a party to the treaty, effectively nullifying President Bill Clinton's signature. Sorry, Mr. President, but you do not get to bomb a country because your country cannot get its act together to ratify a treaty. President Obama has a clear opportunity with the Syrian crisis to submit the treaty for Senate ratification and use his office to secure the required two-thirds vote for approval.
Obama and congressional leaders should not try to kid the American people, or themselves, with fantasies about surgical strikes. Blatant violations of international law and national sovereignty carry emotional weight that lasts for decades. The "surgical coup" of Mohammed Mosaddegh in Iran, in 1953, festered for decades and eventually returned with a vengeance in 1979, when the Mullahs came to power and took American hostages. Moreover, from the German bombing of Britain in World War II to the US bombing of Libya in 1986, surgical strikes have rarely if ever achieved their goals. And these surgeries are fraught with problems and unanticipated consequences. The US air strike against Serbia in 1999 struck the Chinese embassy. The Libyan attack killed three of Qaddafi's children including his 15 month old daughter and hit the French embassy.
Bombing Syria today simply adds a chapter to the book of complaints that could inspire future generations of anti-American terrorists. Many of these complaints are overblown, but this one -- if it happens -- will not be. The first step to stopping war crimes is for good countries to stop committing war crimes. We must not bomb Syria. The second step is to hold those who do perpetrate war crimes accountable, through international institutions like the United Nations, the International Criminal Court, or a broad coalition of governments.
There is no away around it. To end war crimes, you must first stop committing them.