Upon naming Brett McGurk as envoy to anti-ISIL coalition for US — after John Allen declared he steps down from the position over two months ago — President Obama stated that the new envoy's job is going to be focused essentially on convincing the US allies neighboring Syria to stop the flow of foreign fighters and mercenaries to the battlefield.
This statement is a practical demonstration of the American embarrassment after Russia dramatically changed the power balance in Syria, with its military intervention in Latakia — the principle port city in Syria; Tartus – a second largest port city on the Mediterranean coast of the war torn country; then followed by the nonstop air raids with Russian made Sukhoi jets and MI helicopters, as well as the Caliber cruise missiles launched from the Caspian sea.
The US has recently discovered the fact, that stopping the flow of foreign fighters into Syria is a necessary step to make peace in the country. Barack Obama just became aware that the US has the ability to put pressure on Syria's neighbors to stop the flow of foreign fighters of 40 different nationalities into the war torn country.
Washington has altered the mission of the US anti-ISIL coalition envoy — to stop the flow of foreign fighters into Syria, that is when John Allen's job was simply wasting time negotiating with Turkey to authorize the US to use its Incirlik air base in south-western Turkey to presumably target ISIL. This is when the US has the power to simply give orders to Turkey, and the latter one has no other choice than to obey.
Meanwhile, Turkey is one of the main hubs for trafficking fighters and mercenaries into Syria. Moreover, Ankara is training and arming these fighters and is getting involved in shameful deals with ISIL to limit the Kurds, fighting the terrorist monster, and to facilitate the crossing of Turkish agents into Syria.