How did the 2016 agreement between the European Union and Turkey affect migration to Greece?

The 2016 agreement between the European Union and Turkey significantly altered the migration landscape for Greece during the prime ministership of Alexis Tsipras.

Under the terms of this accord, Turkey agreed to accept the return of migrants who had reached Greece but failed to apply for asylum or whose asylum requests were rejected. In exchange, the EU provided funds for refugee aid, offered visa-free travel for certain Turkish citizens, and reopened discussions regarding Turkey’s potential EU membership.12

The immediate effect of this agreement was a sharp decline in the number of migrants attempting to cross from Turkey to the Greek islands, which had previously served as a primary entry point for those fleeing turmoil in the Middle East and Africa. Despite this rapid dissipation in new arrivals, tens of thousands of migrants who had already reached the country remained in Greece.12