After a weekend of artillery strikes against both Kurdish and Syrian military targets, the Turkish government today threatened its “harshest response” yet against the Kurdish YPG if they dare get any closer to the Syria-Turkey border.

The threat comes amid a Kurdish offensive against ISIS, which controls much of the Syrian side of the border in Aleppo Province, and is under growing pressure from several fronts. The YPG seized the town of Tal Rifaat today, just a few miles out of the ISIS territory.

The Kurds blocked the road between Tal Rifaat, held by an Islamist rebel faction, and the border town of Azaz, which Turkey uses to supply various rebel forces with weapons. Reports suggest they took the town with relative ease, as they have other rebel territory in the area.

The YPG and ISIS have fought some protracted campaigns over several key territories across northern Syria, with both sides engaging in some massive offensives against the other. The YPG has been backed by US and Russian airstrikes in different areas, with the US tending to shy away in areas Turkey opposes the Kurds having.

Though Turkish officials denied weekend reports that a handful of soldiers had crossed the border at Azaz to fight the Kurds, they don’t seem to be rejecting the idea of a ground offensive into Syria out of hand, and have recently been in consultation with Saudi Arabia on a joint invasion of the nation.