In an interview on CNN, Panetta said Syria's possession of chemical weapons makes the country's political instability there more dangerous.
A movement that began with large protests in early 2011 against President Bashar Assad has escalated into a civil war.
Panetta said the chemical weapons remain in the custody of the Syrian military, although they have been moved for security reasons.
"We've continued to monitor that. We are working with countries in the region to ensure that we have the best information possible with regards to the sites and how they are being secured," Panetta said.