The Obama administration is weighing options for more direct involvement in Syria's civil war if the opposition can establish a safe zone.

Secretary of State Hillary Rodham Clinton says such a development is only a question of time.

For now, U.S. officials stand by their assertion that they won't provide arms to Syria's anti-government forces or seek a no-fly zone over rebel-controlled areas.

Yet officials are starting an early analysis of how a safe zone might allow them to step up American assistance, limited so far to humanitarian aid and nonlethal equipment such as medical supplies and communications gear.

Clinton said earlier this week the opposition was claiming "more and more territory."

She said a safe haven inside Syria was an eventuality.