WASHINGTON/AMMAN - A Pentagon-backed rebel group and the US-led coalition fighting Islamic State killed more than 20 Islamic State fighters and detained a number of militants in the southern Syrian desert near a base, the coalition said on Thursday. In a statement, the coalition said the Maghawir al Thawra, the rebel group, and the coalition detected a convoy near at-Tanf, near the Syrian border with Jordan and Iraq, early on Wednesday and carried out an operation 'to prevent their further incursion.' 'Despite the presence of Russian-backed, pro-Syrian regime forces in the area, Daesh still finds ways to move freely through regime lines and pose a threat,' Brigadier General Jonathan Braga, the director of operation for the coalition, said, using an Arabic acronym for Islamic State.