Ankara is particularly cautious about an independent Kurdish state arising from a destabilized Syria . Turkey has fought an insurgent war against the Kurdistan Workers ' Party ( PKK ) , a Kurdish guerrilla group ( recognized as a terrorist organization by both the United States and the European Union ) seeking Kurdish independence . Relations between the United States and Turkey have shown signs of deterioration during the Syrian Civil War and especially over the handling over the YPG . The American forces in the Syrian Civil War are openly allied with the Kurdish YPG fighters and support them militarily . The YPG has been criticized by Turkey for its alleged support for the PKK , especially since a rebellion in southern Turkey began in 2015 . Turkey overtly defied American orders of ceasing Turkey 's military bombardment of the YPG fighters in their bid to take the town of Azaz in northern Syria . Signs of strain were then displayed when Barack Obama refused to have a formal meeting with Erdogan when the latter visited the United States in March 2016 . CIA activities in Syria . In early 2012 , the CIA set up in co-operation with Turkey what it called " the Rat Line " , a covert operation to obtain and transport , using proxies and front companies , armaments from Libya to rebel groups rebel forces ( later became Free Syrian Army ) in Syria via southern Turkey as reported by Seymour Hersh . The CIA 's part in the operation reportedly ended as a result of the mass evacuation of CIA operatives from the American consulate in Benghazi , Libya , after the 2012 Benghazi attack . In January 2014 , the House Permanent Select Committee on Intelligence reported specifically on " the CIA annex at Benghazi " that " All CIA activities in Benghazi were legal and authorized . On-the-record testimony establishes that the CIA was not sending weapons ... from Libya to Syria , or facilitating other organizations or states that were transferring weapons from Libya to Syria . " In 2015 , the '' International Business Times '' wrote the U.S. has sent weapons shipments to FSA-identified groups through a U.S. CIA program for years . Timber Sycamore was a classified weapons supply and training program run by the CIA and supported by some Arab intelligence services , such as the security service in Saudi Arabia . Launched in 2012 or 2013 , it supplied money , weaponry and training to rebel forces fighting Syrian President Bashar al-Assad in the Syrian Civil War . According to US officials , the program has trained , thousands of rebels . . In July 2017 , National Security Adviser H. R. McMaster to President Donald Trump and neoconservative CIA Director Mike Pompeo had decided to phase out the support . Following the termination of CIA program best of these forces became Turkish-backed Free Syrian Army
2012 Benghazi attack
2012 Benghazi attack
Turkey–United States relations