BEIRUT -- Syria's main Kurdish party warned Turkey on Wednesday that any military intervention would threaten international peace and said the country's main Kurdish militia is ready to face any "aggression."
Meanwhile, a Syrian rebel group released a video showing 18 Islamic State militants being shot in the backs of their heads.
The statement by the Democratic Union Party, or PYD, comes as Turkish media is abuzz with talk of a long-debated military intervention to push the Islamic State group back from the Turkish border -- a move that would also outflank any Kurdish attempt to create a state along Turkey's southern frontier.
Kurdish fighters backed by U.S.-led airstrikes have been on the offensive against the IS group in northern Syria for months, and now control a long stretch along the Syria-Turkey border. Turkey, which battled a decades-long Kurdish insurgency, has viewed the advance with growing concern and has warned it will not tolerate the establishment of a Kurdish state in Syria.
Two weeks ago, the People's Protection Units, or YPG, which is dominated by the PYD, captured the border town of Tal Abyad, denying the IS group a crucial nearby border crossing used to bring in supplies and foreign fighters.
The capture of Tal Abyad cleared the way for the Kurds to connect their stronghold in Syria's northeast to the once badly isolated border town of Kobani -- where they famously resisted a months-long Islamic State siege -- and possibly extend it to the Kurdish enclave of Afrin in Syria's northwest.
"Any military intervention in Rojava will have local, regional and international repercussions and will contribute to complicating the political situation in Syria and the Middle East and threaten international security and peace," the PYD statement warned. Rojava is a term that refers to Syria's predominantly Kurdish region.
The PYD called on NATO members to prevent Turkey from carrying out any "reckless" intervention. It added that Syria's Kurds want good relations with their neighbors and have no intention to set up an independent state.
Turkish President Recep Tayyip Erdogan chaired a National Security Council meeting Monday which covered developments in Syria. Pro-government newspapers said proposals ranged from loosening the rules of engagement to give Turkish troops a freer hand to fire into Syria, to a tanks-and-troops invasion aimed at occupying a 110-kilometer (70-mile) long, 33-kilometer (20-mile) wide buffer zone.
Turkish officials fear the creation of a vast and contiguous zone of Kurdish control could stir up separatist sentiment among its own Kurdish minority. Ankara is also concerned over reports that Kurdish rebels are chasing other ethnic groups, such as Arabs and Turkmens, out of the areas under their control.
The PYD statement said YPG fighters "are ready to repel any aggression by any party." It called on Turkish officials to "stop their provocative and reckless acts."
Earlier Wednesday, YPG spokesman Redur Khalil said Kurdish fighters now fully control Tal Abyad, after repelling a surprise Islamic State attack that saw the extremists briefly seize the northeastern neighborhood of Mashhour. Khalil said three IS fighters were killed and a fourth blew himself up.
Also Wednesday, the Syrian rebel Islam Army faction released a video showing the shooting deaths of 18 Islamic State militants whom they had been holding. The IS fighters came from Kuwait, Saudi Arabia and other countries.
The Islam Army video came a week after IS released a video showing the beheading of 12 Islam Army members who had been captured by the extremists. The group warned its other rivals to repent or face the same fate.
The Islam Army video showed the 18 IS members in black uniforms with arms and legs shackled as they were pulled by a chain around their necks. The men were made to kneel in a field and their masks removed before each of them was shot in the back of the head.
The video appeared genuine and corresponded to other AP reporting of the events.
Islam Army has fought deadly battles against the Islamic State group over the past year mostly in the suburbs of the capital Damascus. Islam Army leader Zahran Allouch is one of the harshest critics of IS and its leader Abu Bakr al-Baghdadi.