Turkish Prime Minister Binali Yildirim (R)speaks next to US Vice President Joe Biden (L) during a joint press conference following their meeting on August 24, 2016 at the Cankaya Palace in Ankara. US Vice President Joe Biden on August 24, 2016 said Washington had made clear that pro-Kurdish forces in Syria must not to cross west of the Euphrates River, a prospect alarming for Turkey. His comments come after Turkish troops launched an operation inside Syria to cleanse the key town of Jarabulus from Islamic State (IS) jihadists. / AFP PHOTO / ADEM ALTANADEM ALTAN/AFP/Getty Images