The statement adds a further signal that Turkey is losing patience with its American interlocutors and is preparing to launch a cross-border offensive against the Kurdish dominated autonomous region across the border.

Turkey in recent weeks has increased its military presence on the Syrian border, signaling the start of a possible assault on the Kurdish People Protection Units (YPG), which it sees as an extension of the outlawed Kurdistan Workers Party (PKK). The YPG, meanwhile, forms the backbone of the U.S.-led coalition forces fighting against the Islamic State (IS) in Syria.

Washington and Ankara have been discussing Turkey’s demand to establish a buffer zone in the region since December, but they have made no concrete steps toward agreeing on a plan.

“We won’t let this process be dragged out. If our expectations aren’t met, we are fully capable of taking whatever measures [are needed] to ensure our national security,” the state-run Anadolu news agency quoted Aksoy as saying.

“If we cannot find a common ground with the United States, we will be obliged to establish the safe zone by ourselves. We deliver this message to our U.S. counterparts at every level,” he said.

Aksoy’s comments came a day after the U.S. Special Envoy for Syria James Jeffrey told reporters at the U.S. State Department that disagreement over the extent of the safe zone had stalled talks.

Turkey has been pushing for a 30-km buffer zone, while Jeffrey said the United States could accept a zone between five and 14 km with heavy weaponry pulled further back. There have also been “differences of opinion” over the roles U.S. and Turkish forces will play in a safe zone, once it is created.

Aksoy said that negotiations with U.S. delegation would continue on August 5 in Turkey.

Jeffrey led a previous delegation to Turkey on July 21 to discuss with his Turkish counterparts the establishment of the safe zone and Washington's continued efforts to eliminate IS.

Reporter’s code: 50101