The United States could send more troops to Syria to fight the extremist Islamic State group, Defense Secretary Ashton Carter said Sunday on ABC's "This Week." Carter's comments come nearly a month after President Barack Obama first announced the U.S. would send 50 special forces personnel to the region.

"If we find additional groups that are willing to fight ISIL and are capable and motivated, we'll do more," Carter said. "The president has indicated a willingness to do more, I certainly am prepared to recommend he do more, but you need to have capable local forces; that's the key to sustainable victory." 

Pentagon officials, as well as Obama, have long said the U.S. was willing to conduct airstrikes in Syria, though they did not want boots on the ground. The announcement in October to send 50 special forces troops moved away from that stance.

The Syrian civil war, which began with peaceful anti-government protests, has been raging for more than four years now. Pro- and anti-government factions have splintered into sectarian groups. The rise of the Islamic State, an extremist group looking to impose Muslim law on vast swathes of Iraq and Syria, further escalated the conflict. More than 220,000 people have died and several million have been displaced since the start of the conflict.

The U.S. has taken the approach of conducting airstrikes against ISIS targets while training local forces to combat the terror group on their own. Carter's comments to ABC came just one day after the U.S. announced its intention to ramp up airstrikes in the region, the Wall Street Journal reported Sunday.

"What they are doing there is they are enabling local forces, a mixture of Kurds and Syrian Arabs, who want to fight ISIL," Carter told ABC Sunday, adding, "So this small, very elite [U.S.] group, is intended to bring to bear all that the United States can bring to bear, in the way of intelligence, air power and so forth, to help these motivated, capable local forces."