The European Union took in the first batch of Syrian refugees from Turkey on Monday, under a deal struck with Ankara aimed at stemming migration flows into Europe, while more than 200 migrants were returned from Greece to Turkey.
Here are details of the EU-Turkey migration deal, struck on March 18:
Question: What did Brussels and Ankara agree?
Answer: Under the arrangement, migrants reaching the Greek islands from Turkey as of March 20 who do not seek asylum or have their request rejected will be sent back to Turkey. In practice, this is to apply to virtually everyone.
In return for every Syrian sent back from Greece, the EU has pledged to directly take in a Syrian refugee living in Turkey, up to a maximum of 72,000 people.
The EU is also granting Turkey funding for the upkeep of Syrians in the country and is offering progress towards visa-free travel for Turkish citizens visiting the bloc, as well as on Ankara's long-running EU membership bid.
Q: What happened on Monday?
A: Greece returned 202 migrants to the Turkish port town of Dikili, according to the governor of Turkey's Izmir province, Mustafa Toprak. They had all arrived since March 20 and had not filed asylum claims in Greece, the European Commission said.
Prior to Monday, Greece had already returned 147 economic migrants - people not considered to be in need of international protection - to Turkey, under a recently revived bilateral agreement with Ankara.
Also Monday, an initial 43 Syrian refugees were due to be taken from Turkey to the EU: 32 to Germany and 11 to Finland. More are set to be flown to the Netherlands on Tuesday.
Q: When will Greece start returning Syrian asylum seekers to Turkey?
A: This cannot begin until Turkey passes legislation ensuring that all Syrians sent back will be granted sufficient protection in line with international laws. It was not clear Monday when this would happen, but the commission said legislative changes had been "prepared."
Aslyum seekers also have a right to file their claim for individual assessment in Greece and appeal the decision before being returned to Turkey.
Q: On what basis can Greece reject the asylum claims of Syrian refugees or others in need of protection?
A: The Greek parliament has passed a law effectively recognizing Turkey as a safe country that protects refugees in line with international standards. This means that anyone who has crossed Turkey to reach Greece should have filed their asylum request there instead, making their application in Greece inadmissible.
Q: Where are migrants and asylum seekers being kept before their return to Turkey?
A: Under the EU-Turkey deal, they are to be accommodated in reception facilities on the Greek islands. Many of these are closed centres, in line with EU rules allowing for their detention - as a last resort - if there is a risk of them absconding.
Q: Is everyone happy with the arrangement?
A: No. Human rights advocates have slammed the EU-Turkey deal as inhumane and have questioned its legality. Migrants on the Greek islands of Lesbos and Chios on Saturday rallied in protest at the "deportations," while hundreds broke out of a camp on Friday, demanding not to be taken back to Turkey.
Q: What support is Greece getting to carry out the returns?
A: Greece is receiving additional manpower from other EU member states, via the EU border agency Frontex and the European Asylum Support Office (EASO).
By Monday, member states had pledged 702 police officers to escort returnees and 44 readmission experts to help Frontex, while EASO had received offers for an overall 452 asylum officers, interpreters and judges, the commission said. In total, 238 people were sent to Greece at the weekend, on top of just over 740 Frontex and EASO personnel already on the ground.
The pledges to date cover half the overall staffing requested by Frontex and EASO to implement the refugee return programme, while Greece is due to supply a further 1,500 personnel.
The EU has pledged to fund the cost of the migrant return programme, and Athens is also getting emergency funding and material support from the bloc to handle the migration surge.
Q: What will happen to people who arrived in Greece before March 20?
A: EU member states have pledged to take in an overall 66,400 asylum seekers out of Greece, but just 581 have been relocated to date.
Economic migrants are to be sent back to their country of origin.