Turkey will send troops to Syria to protect its border where Syrian Kurds have made significant gains in the past month, several Turkish media outlets reported Sunday. The Turkish government gave its military the directive to increase support to Syrian rebels on the border, something the army has agreed to do on the condition that diplomatic issues with allies were ironed out.

Turkish news outlet Cumhuriyet Daily reported on Sunday that the military had not been deployed but that it was already in planning stages. The deployment of Turkish troops into Syria is likely to be a major game-changer in Syria. Turkey has the second biggest army in NATO and its proximity to Syria has made the country a key player in the American-led coalition to fight the Islamic State group.

Syrian Kurds have been fighting the group also known as ISIS on the Turkish border for the past year, and their recent advances have worried Turkey, which is opposed vehemently to a Kurdish state on its border.

“I am saying this to the whole world: We will never allow the establishment of a state on our southern border in the north of Syria,” Turkish President Recep Tayyip Erdogan said in a speech last Friday. “We will continue our fight in that respect whatever the cost may be.”

The Turkish government has not confirmed or denied the reports, but said the announcement would be made on Tuesday.

“We have a MGK [National Security Council] meeting tomorrow; we will make the necessary announcements afterwards,” Foreign Minister Mevlüt Çavuşoğlu said, according to the state-run news outlet Anadolu Agency.

Turkey has a tumultuous relationship with its own Kurdish population and worried the recent gains would allow their Syrian counterparts to consolidate territory from Kobani to the Kurdish canton of Afrin. Kurdish leaders have denied they have plans to do so.

Turkey’s alleged “active support” for Syrian moderate rebels with the Free Syrian Army would involve roughly 18,000 ground forces, air support and artillery on a stretch of land spanning from Kobani to Mare, an FSA-controlled town in northwestern Syria, the Daily Beast reported, citing local media reports.

Syrian rebels have, in some cases, participated in Kurdish offensives to push back ISIS militants in the border area with Turkey. Turkey said will support the rebels in pushing back both ISIS and Kurdish forces from the border.

Earlier this year, Syrian Kurds were largely fighting in the border town of Kobani where ISIS was pushed out in January. Early last week, Syrian Kurdish People’s Protection Units seized Tel Abyad, cutting off a key supply route from Turkey to the ISIS de-facto headquarters in Raqqa. By the end of last week ISIS launched a major assault to retake Kobani, killing at least 200 people.