The rebel group that led the ouster of Syrian President Bashar al-Assad - Hayat Tahrir al-Sham (HTS) - has long been under United Nations sanctions, which the U.N. special envoy for Syria Geir Pedersen has described as "a complicating factor for all of us.

Syrian rebel forces led by Hayat Tahrir al-Sham, or HTS, declared they had ousted President Bashar al-Assad and he had fled Damascus on Sunday. But what is HTS, and how did it rock the long-simmering tensions in Syria? HTS is a Sunni Islamist militant and political group that traces its roots to the beginning of the Syrian civil war.

Sham, or HTS, that took over Syria and ousted President Bashar al-Assad, has yet to show how it plans to govern the country torn by more than a decade of civil war. CBS News contributor Sam Vinograd breaks down what's known about the opposition group in power.