Earlier in the day, US Secretary of State Mike Pompeo said that ensuring the Turkish military didn't massacre Kurds would be a key priority as US forces were leaving Syria.

Earlier in the day, Middle East Eye reported citing unnamed sources that President Donald Trump had sought assurances from Erdogan that a Turkish move against Kurdish forces in Syria would not create a humanitarian crisis.

Trump has faced tremendous pressure to protect US-backed Kurdish forces belonging to the People's Protection Units (YPG) in Syria, the most effective American-backed force in liberating the city of Raqqa and other areas seized by the Islamic State (IS).

Erdogan has warned of a fresh Turkish offensive against the YPG, which he considers a terrorist group.

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