Is America planning to attack Syria?

He expressed concern about stepped-up intervention leading to “unintended consequences.”

For all the talk about policy changes, American officials remain hampered by the same constraints that have stymied the U.S. response throughout the three-year civil war, including concern that lethal assistance could end up in the hands of extremists.

And then there also is Obama's own distaste for military action.

After more than a decade of fighting in Afghanistan and Iraq, Obama has desperately sought to avoid embroiling the U.S. in another deadly and inconclusive war.

He backed away last year from his threat to take military action in response to a Syrian chemical weapons attack when it became clear Congress would not vote its approval.

Even options short of direct strikes pose difficulties.

Grounding Assad's air force by enforcing a no-fly zone in Syria would most likely require a large-scale attack on the military's advanced air defense systems.

Military support for the opposition continues in the form of small weapons and ammunition.