WASHINGTON - Joint Chiefs Chairman General Martin Dempsey says U.S. forces stand ready to take military action in Syria -- but warns a no-fly zone in the country may not work.

"Whether the military effect would produce the kind of outcome that all of us would desire - an end to the violence, some kind of political reconciliation among the parties and a stable Syria - it's not clear to me that it would produce that outcome," Dempsey said Tuesday at a Christian Science Monitor luncheon. "Options are ready," Dempsey continued. "And if it becomes clear to me or if I'm ordered to do so we will act, but at this point, that hasn't occurred."

While no specific details were provided on those options, Dempsey was clear that despite new intelligence indicating chemical weapons have been used in Syria, America's military posture remains the same.

"Nothing I've heard in the last week or so has changed anything about the actions we're taking as a military," he said. "We've been planning, we've been developing options, [and] we are looking to determine whether these options remain valid as conditions change. That doesn't mean that what's happened over the last week wouldn't change the policy calculus - but militarily our task has been to continue to plan, to continue to engage with partners in the region, and to continue to refine options so that if we're asked to implement any - we'll be ready."

President Barack Obama has said if the Assad regime uses chemical weapons it would be a 'game changer' and such action would cross a 'red line.'

Asked if crossing that line obligates a military response, Dempsey quipped, "You're asking the wrong guy. I don't set red lines. I didn't set red lines on the budget, I didn't set red lines on our military activities across the globe, I simply prepared for options when asked to produce them."

The nation's top military officer is offering a warning of his own -- against comparing the situation in Syria to the conflict in Libya. He specifically cited the challenges posed by Syrian air defense systems, which come from Russia.

"In Syria you've got I think 5 times more air defense systems - some of which are high end air defense systems - and more importantly they're all collapsed into the western third of the country. So [it's] a much denser and more sophisticated system," he said. "Now the United States military has the capability to defeat that system, but it would be a greater challenge, take longer and require more resources."