Vice president Joe Biden said a political deal would be better, but if that’s not possible the US would pursue other alternatives.
The US has been bombing ISIL (the Islamic State in Iraq and the Levant) since June 2014 but has so far not committed ground forces for direct involvement in the conflict.
Mr Biden was speaking on Saturday after meeting Turkish PM Ahmet Davutoglu in Istanbul.
"We do know it would better if we can reach a political solution but we are prepared ..., if that's not possible, to have a military solution to this operation in taking out Daesh," Biden said at a news conference after the meeting, the Telegraph reported.
Dozens of US special forces are already in Syria, although US claims the troops are not intended for front line combat.
The latest round of Syria peace talks are planned to begin on Monday in Geneva, but were at risk of being delayed over disputes about who would form the opposition.
A US official later said that Biden was talking about a military solution to Daesh, not Syria as a whole.