As an agreement between the European Union and Turkey aimed at stemming the flow of migration to Europe went into effect Sunday, asylum-seekers both on their way to Europe and already arrived looked to cope with the immediate consequences of the deal. While the policy that will resettle one Syrian refugee in a Turkish camp in Europe in exchange for one Syrian returned from Greece does not begin until early April, the deal will have immediate consequences for asylum-seekers already in Greece, as well as those who continue to land in smugglers’ boats across the Greek islands.

More than 1 million people sought asylum in Europe in 2015, with more than 150,000 arrivals in the first months of 2016. The vast majority of people arriving in Europe are refugees, according to the United Nations, which defines a refugee as someone fleeing political violence, persecution or the threat of death in his home country. Nearly 50 percent of the refugees who have arrived in Europe through Greece are from Syria, where the five-year civil war has displaced millions and left several hundred thousand people dead.

The deal seeks to crack down on smuggling and cope with the ongoing crisis by processing asylum claims in Greece and returning those who don’t seek asylum or whose claims are denied. For each Syrian sent back to Turkey from Greece, the EU has promised to resettle one Syrian who is already in a Turkish refugee camp. Here’s a breakdown of what the deal looks like for asylum-seekers depending on where they are:

What happens to refugees already in Northern Europe? Asylum-seekers who made the journey from Greece up through the so-called Western Balkans route to Northern European destinations of resettlement, such as Germany or Sweden, before the agreement was struck will not fall under the umbrella of this deal. Asylum-seekers in those countries are regulated by national authorities and can be granted or denied asylum based on decisions made by immigration authorities in those countries.

What happens to refugees who have been waiting in Greece for some time? The deal focuses primarily on Greece, a nation that has served as a popular point of first entry for refugees from the Middle East because of its proximity to Turkey. Asylum-seekers who arrived in Greece before March 20 are still eligible for EU relocation, which entails applying for asylum and being either denied and returned to Turkey, or accepted and given an offer from a member state that has agreed to the plan. Asylum-seekers cannot choose the country to be relocated to in this case.

What happens to newly arriving refugees in Greece? Those who arrive after March 20 no longer qualify for relocation and can apply for asylum only  in Greece — a country that few want to settle in owing to its slow economic growth and high unemployment rate. Those who are denied asylum in Greece or who do not apply will be returned to Turkey under the new deal.

Will the plan stop the flow of refugees into Western Europe? Critics of the deal, particularly from humanitarian organizations, have said this system will not achieve its goals as it does not take into account the determination and goals of asylum-seekers fleeing violent conflict. “Despite what the EU council might say, a plan that aims at stopping these people from seeking asylum in Europe and returning them massively to Turkey — a country that is already hosting close to 3 million registered refugees — is likely to produce additional human suffering and is also completely unrealistic,” Aurélie Ponthieu, a humanitarian adviser for the nonprofit Doctors Without Borders, said Friday.