There is evidence that Syria is preparing for a chemical attack against its own people. This is the same kind of weapon that Saddam Hussein used on his own people in the 1990’s when President HW Bush had promised rebels if they rose up against Hussein, the US would be there to help. Hundreds of thousands were killed and the US and rest of the global community did nothing.
Certainly, nations have a right to their sovereignty — that’s why no one invaded the US when we foolishly re-elected President GW Bush despite the world’s horror that happened. However, the international community defines sovereignty in terms of the peoples’ sovereignty, placing human rights above the rights of the state/ rulers. The world community has a responsibility to protect human rights on a mass scale. And yes, we’re hypocritical when we do (since we largely ignore the state-sponsored atrocities of Israel and China as obvious examples) and even worse when we ignore it (how about sub-Saharan Africa?). Yet, in a meaningful way, these examples are different than Syria — to prevent the use of chemical weapons is a matter of specific strategic bombing versus trying to sort out an entire system. To prevent a chemical weapons attack is not the same thing is disposing a government. Think of this as a referee function within the world community — this is mitigating an already unfair advantage as factions within Syria vie for the country’s control.
Civil wars are going to happen in unsettled places and it’s important that these be allowed because people must determine for themselves; however, there must also be limits. Weapons of mass destruction should never be used, let alone against a country’s own people because there is no way for a nation to recover from that. In the United States — nearly 150 years after the end of the civil war — there are still cultural, social, attitudinal, and political divides between the South and the rest of the country. Imagine the lasting social and political devastation that using chemical weapons would have on the fabric of a nation — especially one whose fabric has already been weakened.
Invade Syria? No. Arm rebels? Probably not. Ensure that chemical weapons are not used? Absolutely.