Turkish troops have begun a ground offensive against Kurdish fighters just hours after launching airstrikes in north-eastern Syria.
The land assault, alongside the Syrian National Army, comes after US forces began withdrawing from the region.
Turkish President Recep Tayyip Erdogan confirmed the news on Twitter.
He wrote: "Our aim is to destroy the terror corridor which is trying to be established on our southern border and to bring peace and peace to the region".
The country is targeting Kurdish fighters, who it sees as terrorists.
The Kurds have helped the West defeat Islamic State, and now run the prisons and camps housing tens of thousands of IS fighters and their families.
Here at home Tanaiste Simon Coveney says he's "deeply troubled" by the situation and the action by Turkey risks undermining the progress made in fighting Islamic State.
Donald Trump has also warned Turkey he'll "wipe out" their economy if they "wipe out the Kurds" in northern Syria.
Meanwhile the UK, France and Germany have demanded a UN meeting to discuss the situation.