Turkey's President Tayyip Erdogan makes a speech at the Turkish Military Academy in Ankara, Turkey January 24, 2019. Cem Oksuz/Turkish Presidential Press Office/Handout via REUTERS

ISTANBUL (Reuters) - Turkey is aiming to form safe zones in northern Syria so that around 4 million of Syrian refugees hosted by Turkey could return, President Tayyip Erdogan said on Monday.

Speaking in Istanbul, Erdogan also said nearly 300,000 Syrians had already returned and that he expected millions of Syrian nationals would return to the safe areas.

U.S. President Donald Trump announced in December the withdrawal of all U.S. troops from Syria and Erdogan subsequently said they had discussed setting up a 20-mile-deep safe zone in Syria along the border.