Turkish President Recep Tayyip Erdogan.

Turkey has warned the United States and Russia it will not tolerate Kurdish territorial gains by Kurdish militia close to its frontiers in northwestern Syria, two senior officials said.

“This is clear cut for us and there is no joking about it,” one official said of the possibility of Syrian Kurdish militia crossing the Euphrates to extend control along Turkish borders from Iraq’s Kurdistan region toward the Mediterranean coast.

Turkey fears advances by Kurdish YPG militia, backed by its PYD political wing, on the Syrian side of its 900 km border will fuel separatist ambitions among Kurds in its own southeastern territories. But Washington has supported YPG fighters as an effective force in combating Daesh.

“The PYD has been getting closer with both the US and Russia of late. We view the PYD as a terrorist group and we want all countries to consider the consequences of their cooperation,” one of the Turkish officials said.

Turkey suspects Russia, which launched air strikes in Syria two weeks ago, has also been lending support to the YPG and PYD.

“With support from Russia, the PYD is trying to capture land between Jarablus and Azaz, going west of the Euphrates. We will never accept this,” the official said.

He said Turkey had raised its concerns at high-level meetings with the US, European Union and Russia.

The officials did not say what action, if any, Turkey might take if YPG forces crossed the Euphrates.

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