The U.S. State Department on Friday repeated its commitment to a political transition "away from" Syrian President Bashar al-Assad after a U.S. special envoy held talks in Moscow on how to end Syria's more than four-year civil war.

"The United States remains strongly committed to achieving a genuine, negotiated political transition away from Bashar al-Assad that brings an end to the violence," it said in a statement.

"Assad's continued tenure fuels extremism and inflames tensions in the region. That is why a political transition is not only necessary for the good of the people of Syria, but an important part of the fight to defeat the extremists."