"If the U.S. goes in and attacks another country without a U.N. mandate and without clear evidence that can be presented, then there are questions in terms of whether international law supports it - do we have the coalition to make it work?" Obama said in the interview broadcast Friday. "Those are considerations that we have to take into account."
Hagel offered no hints Sunday about likely U.S. response to Syria's purported use of chemical weapons, telling reporters traveling with him in Malaysia that the Obama administration was still assessing intelligence information about the deadly attack.
"When we have more information, that answer will become clear," he said when a reporter asked whether it was a matter of when, not if, the U.S. will take military action against Syria.
Asked about U.S. military options on Syria, Hagel spoke in broad terms about the factors Obama is weighing.
"There are risks and consequences for any option that would be used or not used - for action or inaction," he told reporters. "You have to come to the central point of what would be the objective if you are to pursue an action or not pursue an action. So all those assessments are being made."
If the U.S. wants to send a message to Assad, defense officials have previously indicated the most likely military action would be a Tomahawk missile strike, launched from a ship in the Mediterranean.
Gen. Martin Dempsey, chairman of the Joint Chiefs of Staff, said in a letter to a congressman last week that the administration opposes even limited action in Syria because it believes rebels fighting the Assad government wouldn't support American interests if they seized power. He said while the U.S. military could take out Assad's air force and shift the balance of the war toward the armed opposition, but that it's unclear where the strategy would go from there.
Dempsey is now in Amman, Jordan, set to meet with Arab and Western peers later Sunday to discuss ways to bolster the security of Syria's neighbors against possible attacks, chemical or other, by Assad's regime, a Jordanian security official said.
The meeting, closed to the press and held at an unspecified location, gathers chiefs of staff from Britain, France, Germany, Italy, Canada, Turkey, Saudi Arabia, Qatar and Jordan, the official said on condition of anonymity because he is not allowed to brief reporters.