Assad is a dangerous terrorist who has broken international laws by using chemical weapons. He has murdered innocent people, and the international community should join together and force him to stand trial for his crimes. This is clearly a case when war is justified. Assad will continue to kill civilians until he is stopped.
If other countries get involved in Syria's civil war, a regional or worldwide conflict could ensue. The regime is backed by Russia, a country that sells arms to Assad's forces. The rebels are backed by almost everyone else. Even the United States has considered sending arms to the rebels. Another country shouldn't attack Assad whatsoever because it risks a spiraling world war, which is what happened in World War I.