Hagel made the remarks at a joint press conference in Washington with British Defense Secretary Philip Hammond on Thursday.
“Arming the rebels – that’s an option,” Hagel said, adding that a “range of options” remained on the table.
“These are options that must be considered with partners, with the international community: what is possible, what can help accomplish (our) objectives,” he said.
Saying that the British government has not directly supplied arms to the militants in Syria, Hammond confirmed that Britain does not rule out the possibility to do so in the future.
The British defense secretary also said the US decision to provide weapons to the militants is a signal that Washington was showing renewed leadership over the Syrian crisis.
“There are plenty of arms getting in there, the difference if the US started supplying arms it would be a sign of leadership and direction,” Hammond said.
“The Saudis, the Qataris and others are pushing arms into Syria but none of those countries can provide the sense of leadership that the US doing it can,” he added.
The US and its allies have been pushing for military intervention in Syria in recent weeks.
On April 28, US Republican lawmakers urged President Barack Obama to intervene militarily in Syria in order to “resolve” the crisis in the Arab country.
The lawmakers pressed Obama to take further action in Syria, saying without intervention, the entire region will “fall into chaos” by the end of the year.
Sen. Lindsey Graham (R- South Carolina) said that Washington could bomb the Syrian air bases with cruise missiles but cautioned against sending in troops.
Sen. John McCain (R- Arizona) also said the United States should go to Syria as part of an international force to secure Syria’s chemical weapons. He noted, however, that he was against sending US troops into the country.
The lawmakers’ comments came after the US and its allies said there was evidence that the Syrian government may have used chemical weapons in its fight against the foreign-backed militants.
Damascus has rejected the accusations as a barefaced lie, repeatedly saying that it will not use chemical weapons in an attempt to end the unrest in the country.
The White House had previously described any use of chemical weapons in Syria as a “red line,” which could trigger possible military action.
On Wednesday, Syrian Ambassador to the United Nations Bashar al-Jaafari said the foreign-backed militants in the Arab country used chemical material against civilians during an attack on a town near Idlib.
Syria has been gripped by a deadly unrest since March 2011, and many people, including large numbers of government security forces and army personnel, have been killed in the violence.
Damascus says the chaos is being orchestrated from outside the country, and there are reports that a very large number of the militants are foreign nationals.