Thousands of migrants and refugees were on the move last week after Turkey's president said the country would stop controlling its land and sea borders with Europe. Taking advantage of the open passage, crowds of people rushed the border only to find the door shut in their faces.

Greece, which has been overwhelmed by migrants seeking safety since 2015, has taken some of the most drastic measures to date to repel potential asylum-seekers. It deployed navy warships to protect its islands and helicopters to guard its land borders. Video surfaced recently of the Greek coast guard pushing back boats loaded with migrants. 

Treating it as a siege, the country also announced it would deport anyone who made it into their territory. Going against international protocol, of which Greece is a signatory, the country said it would suspend all asylum applications for a month, effectively sealing off its borders to anyone in need of humanitarian aid. 

"Our national security council has taken the decision to increase the level of deterrence at our borders to the maximum. As of now we will not be accepting any new asylum applications for one month. We are invoking article 78.3 of the TFEU to ensure full European support," wrote Greek Prime Minister Kyriakos Mitsotakis on March 2, referencing the Treaty on the Functioning of the European Union (EU).

The UN's refugee agency said there is no legal basis for Greece's refusal to accept asylum applications.

On the other side of the border, Turkey warned Europe that "millions" of migrants and refugees will head towards its shores. The move made good on Turkish President Recep Tayyip Erdogan's previous threat to "unleash" the more than four million refugees that live in the country.

While Turkey has argued that the EU has not lived up to its commitments in a 2016 deal to manage migration to Europe, it is also looking for support in its offensive in neighboring Syria. Turkey suffered more than 30 casualties in an airstrike in Syria on February 27. The day after, Erdogan ordered Turkish police, coast guard and border security to stand down and allow migrants through. 

With both parties accusing each other of reneging on the deal, the EU-Turkey statement is on the verge of collapse. Now at a standstill, the EU and Turkey agreed on Monday to reevaluate the EU-Turkey statement in the coming days. Financial and political concessions will be on the table, but with thousands of asylum-seekers caught in the space between a Turkey that sees them as leverage and an EU that views them as a menace, the two parties are forced to come to terms with what to do with asylum-seekers that nobody seems to want.

A shaky EU-Turkey deal

Though the number of hopeful refugees rushing to Europe now is nowhere near the millions that Erdogan claims, the surge is reminiscent of what Europe called its migrant crisis in 2015, when more than 1.3 million refugees sought asylum in Europe. 

One of the most critical elements of Europe's response to the outbreak was the 2016 EU-Turkey deal, a controversial agreement between the bloc and Turkey that is now at risk of falling apart.

Built as a reactionary measure and implemented on March 20, 2016, the deal was aimed at stopping the waves of people reaching Greece. The deal essentially said to every potential refugee – ask for asylum in Turkey, rather than Europe, and we will protect you. 

It enabled Turkey to take measures to prevent migrants from reaching Greece, a key point of entry to Europe. An essential part of the deal involved what was called a "1:1 scheme," where Greece and Turkey essentially traded an irregular migrant, or someone who entered illegally, for an accepted refugee. For every irregular migrant Greece would deport to Turkey, Turkey would then send an accepted refugee to Greece, and later onto the EU. 

Turkey would also be responsible for hosting and processing asylum applications in exchange for financial compensation from the EU. The bloc agreed to resettle and relocate accepted refugees from Turkey. 

The incentives for each stakeholder were clear. For the EU, it was a way to prevent migrants from coming, for Turkey it promised a reevaluation of its ascension to the EU, and for asylum-seekers, it offered the chance of resettlement, or at least the hope of being considered for new lives in a European country – if they stopped coming to Europe first.

Yet, structured this way, "The EU-Turkey deal was really their answer to how do we stop having to accept large numbers of humanitarian migrants in Europe, which is a way of sidestepping obligations they have under international law," said Dr. Jacqueline Bhabha, a professor of health and human rights at Harvard and author of the book "Can we solve the migration crisis?"

While the deal did make it more difficult for migrants to come to Europe, it did not do much to ease the humanitarian burden on Greece and Turkey, the two countries under the most migrant pressure. 

Immediately following the deal, Greece went from about 1,680 sea arrivals per day to an average of 80 per day. In the three months before the agreement was signed, more than 150,000 people landed on Greek shores. For the remainder of that year, only about 22,000 asylum-seekers arrived.

Though they may have stopped coming to Europe, the deal meant that they were contained elsewhere. While the deal "worked in the sense that it decreased the number of irregular arrivals, what happened was that people were contained in Turkey," said a Turkish academic who preferred to remain unnamed.

With the Syrian civil war going into its ninth year, the number of refugees worldwide has ballooned to the highest on record. Last year, the UNHCR recorded more than 70 million people displaced worldwide, among which 6.7 million were Syrian refugees. 

Regionally, the majority of the humanitarian burden has been placed on Turkey which shelters the world's largest refugee population at nearly four million. At the same time, more than 42,000 migrants live in precarious conditions in camps meant to only house 9,000 on the Greek islands.

Within the EU-Turkey deal, the bloc has only resettled 21,000 refugees as of March 2019.

How will the EU deal with another migrant crisis?

With the threat of a new migrant crisis, Greece and Turkey are both doubling down on both of their borders, subsuming the future of refugees and asylum-seekers into a discussion about border control.

"The borders of Greece are the external borders of Europe. We will protect them," wrote Greek Prime Minister Kyriakos Mitsotakis on Twitter on March 2, adding "Once more, do not attempt to enter Greece illegally – you will be turned back."

The prime minister's statement puts security at odds with humanitarian obligations and calls into question whether a country can protect both its borders and refugees and asylum-seekers. 

The original EU-Turkey deal was Europe's attempt to accomplish both objectives. Structured in a way that was part deterrence, part humanitarian – it called for curtailing the flow of people arriving in Europe first, and then promised to provide protection to those in need.

It's this second part of the deal that Turkey is now accusing the EU of failing to fulfill.

In pledging to keep Turkey's border to Europe open, Turkish President Erdogan stated, "We will not close those doors… Why? Because the European Union should keep its promises.”

Turkey's sudden reversal on the deal challenges the sustainability of the strategy of deterrence. Rather than solving the needs of refugees, it redirects them to a different location, which up to now has been Turkey. 

"If you don't address the very severe fact that's precipitating people to decide to come, these deals don't really solve the problem, they just push it to a different place," said Dr. Jacqueline Bhabha, whose work focuses on human rights and migration at Harvard. 

Backed by Russian forces, the Syrian government has continued its heavy bombardment of towns and villages in Idlib, the last province held by the opposition. Nearly a million people have fled in the last three months, trickling out to Turkey, Jordan and Europe in the largest exodus since the war started in 2011. 

The surge in new arrivals from Idlib was a breaking point for Turkey. "With the new arrivals arriving at the border from Idlib, it became really stark that Turkey couldn't handle people and just keep them inside," said the Turkish academic.

Whether propelled by Turkey or not, there is concern that the crisis facing refugees will once again become Europe's crisis. The difference this time is that the bloc has the experience of the past four years to learn from, and decide whether it will revert to the same strategies of containment.

UN High Commissioner for Refugees Filippo Grandi recently appealed to countries to broaden up admissions and legal pathways for asylum-seekers.

"Thousands of innocent people cannot pay the price for a divided international community, whose inability to find a solution to this crisis is going to be a grave stain on our collective international conscience."