The international community is watching the civil war in Syria amid allegations both sides used chemical weapons. Obama said chemical weapons may trigger a strong response from the United States but said he was proceeding with caution.
Defense Department spokesman George Little said the U.S. military was considering a range of options for Syria.
"We continue to refine those plans based on how the conflict is unfolding and based on information we receive," he said. "That's our responsibility and we believe it is important to have options on the shelf to pull off in case the president looks to us to execute those options."
Little added that concerns in Syria extend beyond the use of chemical weapons.
U.S. Joint Chiefs of Staff Chairman U.S. Army Gen. Martin Dempsey spoke this week, at an event hosted by The Christian Science Monitor, of the challenges in addressing a situation like Syria.
NATO forces set up missile defense systems in Turkey to prevent spill over. Dempsey said establishing a no-fly zone, however, could involve the United States deeper into a civil war between President Bashar Assad and anti-government forces.
Little said the military was working with its partners "on how to look at the situation in Syria and act if necessary."