Published: Apr 26, 2013 6:26 AM EDT
Updated: Apr 26, 2013 6:27 AM EDT

WASHINGTON (AP) - The White House disclosure that the Syrian government has twice used chemical weapons still leaves the Obama administration stuck with a limited choice of military options to help the rebels oust President Bashar Assad.

Arming the rebels runs smack into the reality that a military group fighting alongside them has pledged allegiance to al-Qaida. Establishing a no-fly zone poses a significant challenge as Syria possesses an air defense system far more robust than what the U.S. and its allies overwhelmed in Libya two years ago.

President Barack Obama has declared that the Assad regime's use of chemical weapons a "game changer" that crosses a "red line" for a major military response. But the White House made clear Thursday that even a quick strike wasn't imminent.