"Did this satisfy us in full?" "The establishment of a so-called terror army would cause irreversible damage in our relations.it is a very serious situation", he warned. Ankara has been enraged by Washington's alliance with the YPG, which led the battle to oust IS from Raqqa, the terror group's self-proclaimed capital, and a swathe of territory across northern Syria. Russian Foreign Minister Sergey Lavrov the plan indicated that the U.S. was planning to partition Syria. The region is controlled by Syrian-Kurds who have strong support from the United States military.
"It is vital for the United States to remain engaged in Syria", he said in a speech to a us research organization audience.
U.S. Secretary of State Rex Tillerson said U.S. troops would stay in Syria for the foreseeable future to defeat jihadists, and said the U.S. would not fund the reconstruction of any part of Syria where President Bashar Assad is in power.
But some analysts warn US plans are insufficient to fulfill the aims outlined by Tillerson.
The Syrian official said the U.S. decision "came within the framework of its destructive policies which aim at fragmenting the region, fueling tensions and conflicts and hindering solutions to its crises".
Tanks are already massed on the border near Afrin, which is held by Kurdish fighters Turkey considers terrorists.
On the other hand, the top Turkish diplomat said that Turkey would intervene in Syria's Afrin and Manbij, due to the threat posed by the Kurdish militants. He did not elaborate on how a major Turkish force crossing the border into Syria to attack Syrian militias would not threaten Syria's territorial integrity.
"As we did during the Euphrates Shield, we are again ready for cooperation with Turkey", he said, referring to a successful Turkish-led operation against Daesh, which ended in March 2017.
A YPG spokesman in Afrin, Rojhat Roj, said new Turkish reinforcements could be seen arriving at the border overnight.
Meanwhile, Turkey's chief of military staff and the head of its intelligence agency travelled to Russia for talks expected to touch on the possible Turkish offensive in Afrin, where the Russian military is believed to have a presence.
Tensions between U.S. and Turkey - two North Atlantic Treaty Organisation allies - remain high, despite Trump saying last November that Washington would no longer supply weapons to the YPG.