US President Donald Trump has threatened Turkey with economic devastation if it attacks a US-allied Kurdish militia in Syria.
Trump's decision to pull American troops out of Syria has left the United States' Kurdish allies in the war against the Islamic State group vulnerable to an attack from Turkey.
Ankara views the US-backed Syrian Kurdish forces as terrorists aligned with insurgents inside Turkey.
Turkey's presidential spokesman Ibrahim Kalin responded to Trump on Twitter by saying: "Terrorists can't be your partners & allies." He also insisted that Turkey "fights against terrorists, not Kurds" as a people.
In Sunday's tweet, Trump also warned the Kurdish forces not to "provoke Turkey."