DENVER - Evidence continues to mount pointing to the regime of Bashar Assad as being responsible for the chemical weapons attack on civilians outside of Damascus on August 21. U.S. military assets have been moved into position to strike at Syria.

Determining how broad that attack should be is a complex issue.

"It is not simple at all and it is becoming more and more complicated as we are moving forward," said Dr. Shaul Gabbay, an expert in Middle Eastern affairs.

Gabbay points to possible opposition to any military attack on Syria by the Russian and Chinese governments. He also says toppling the Assad regime could plunge the country into chaos that could spread beyond the Syrian borders.

"Our most important interest is stability, particularly in a region which is volatile and very important to us," says Gabbay.

If the Assad regime were toppled it would also call into question who would seize control of the government. The opposition groups fighting the Assad regime is a wide ranging collection of forces. Some of those are aligned with al-Qaeda and Hezbollah.

"There are a lot of people in that opposition and some of them are people who share a vision of democracy, no question. But some of them are people who share a something we really don't want to see any more of," said Christopher Hill, the former U.S. Ambassador to Iraq and Dean of the Josef Korbel School of International Studies at the University of Denver.

Hill says the U.S. may also look at imposing a no-fly-zone in Syria to prevent future chemical weapon attacks. A similar no-fly-zone was successfully used in Kosovo to prevent ethnic cleansing by the Serbs.

Both Gabbay and Hill believe any response by the U.S. and their allies will be to punish the Assad regime while not toppling it.

"Once they get ready, what they will eventually do is some kind of punitive attack to make clear to those who engage in the use of banned weapons that they really shouldn't do that," said Hill.

Hill also believes it is important to send that message so that others possessing weapons of mass destruction will think twice before deploying them.

"I think it is very important to make clear to anyone considering the use of banned weapons, whether it is chemical, biological or nuclear that they will not be able to deploy those weapons with impunity and that they will be hit and hit hard. So I think it is an important message to send," said Hill.