What's the story?

Germany's chancellor, Angela Merkel, told Turkey it was "unacceptable" to pressure the EU "on the backs of refugees," as thousands of asylum seekers, many fleeing war in Syria, were encouraged by Turkey to try to enter the bloc via neighboring Greece, Bulgaria and Hungary on Monday.

Merkel's comments come after Turkey's president Recep Tayyip Erdogan's announced late last week the country would stop enforcing a 2016 agreement that had prevented its 3.7 million Syrian migrants from reaching the European Union in return for aid. 

While acknowledging the "additional burden" on Turkey in the escalating migrant crisis, Merkel added: "I find it completely unacceptable that ... Erdogan and his government did not bring their dissatisfaction to us at the EU, but instead duked it out on the backs of refugees."

Meanwhile, EU migration commissioner Margaritis Schinas said that "no one can blackmail or intimidate the EU," at a separate Berlin event, proclaiming the need for unity within the bloc.

How was this point reached?

On Sunday, Greece's prime minister Kyriakos Mitsotakis blocked all new asylum applications to the country for one month and warned migrants from Turkey not to "attempt to enter Greece illegally." Adding: "You will be turned back."

Mitsotakis also announced plans to beef up border security.

"The borders of Greece are the external borders of Europe," wrote Mitsotakis on Sunday evening. "We will protect them."

How have others reacted to Greece's asylum ban?

The United Nations High Commissioner for Refugees (UNHCR) said Greece has no legal justification for suspending such protocols.

"Neither the 1951 Convention Relating to the Status of Refugees nor EU refugee law provides any legal basis for the suspension of the reception of asylum applications," the agency said in a statement, adding that it should be the EU that had the right to enforce such measures, not individual member states.

"[Greece] cannot suspend the internationally recognized right to seek asylum and the principle of non-refoulement [no push-back] that are also emphasized in EU law," it said.

What's happening at the Turkey-Greece border? 

Greek officials have accused Turkey of a "guided and encouraged" effort to drive more than 10,000 migrants, mostly from Syria, other Middle Eastern states and Afghanistan, to its land borders with EU states Greece and Bulgaria after Ankara's decision to stop keeping them on its territory. 

There have been some violent clashes in Kastanies, a town about 900 kilometers north-east of Athens in the Evros province. Greek and Turkish police fired tear gas into crowds caught between the fences in no-man's land over the weekend, with some migrants throwing stones, metal bars and gas canisters.

Migrants on the Turkish side of the border, some holding white flags, called on the Greek soldiers and riot police to open the gates to let them through, saying they had women and children with them.

Greece's Skai TV said Greeks were using loudspeakers in the border area to tell migrants, in English and Arabic, that they were not welcome, shouting: "The Borders are Shut."

Some migrants scaled a three-meter fence covered in barbed wire nearby, while others, such as Therose Ngonda, a 40-year-old woman from Cameroon, waded across the Evros river's fast-moving waters. She said she had been told migrants had 72 hours from Friday to leave the country, having been one of about 2,000 people bused to the border from Istanbul.

The people caught up in the increasingly volatile stand-off between the two countries are now left to face winter weather and further uncertainty.

What's the situation on the sea borders?

More than 40,000 migrants still living on Greece's Aegean islands in the severely overcrowded camps that have been erected since the 2015 crisis and authorities say at least 1,000 migrants have reached the islands since Sunday morning.

The coastguard claims a boat that capsized off Lesbos on Monday morning, carrying 46 people, had been escorted there by a Turkish vessel. One child drowned in the incident.

Another dinghy containing about 30 Afghans arrived on Lesbos early in the morning, according to Reuters. While 32 others were rescued in the seas off Farmakonisi, a small island close to Turkey, the coast guard said.

"This is an invasion," development minister Adonis Georgiadis told Skai TV on Monday.

Why are there so many migrants now?

The escalation comes as a direct consequence of the killing of 33 Turkish soldiers by government forces in Syria's Idlib region.

Erdogan has long accused the EU of failing to provide enough support to Ankara in promised aid since reaching a deal to house the migrants indefinitely in 2016. The year before, nearly a million refugees crossed from the Turkish border to the Greek islands to spark a migrant crisis in Europe in which 4,000 people drowned in the Aegean Sea.

On Thursday, Erdogan's patience snapped, saying Turkey could no longer hold the refugees.

What is the EU going to do?

With Greece invoking an emergency EU clause "to ensure full European support" of the decision to stop accepting new asylum applications (which is technically not permitted by EU law), the bloc is ready to involve its border agency Frontex to mediate and support. 

Ursula von der Leyen, president of the European Commission, expressed sympathy on Monday with Turkey over the conflict in Syria, but said its decision to let refugees and migrants cross into Europe "cannot be an answer or solution."

Where do they go from here?

In a tweet on Sunday, Greek PM Mitsotakis said he would visit the Evros land border with Turkey on Tuesday, along with EU president Charles Michel, as claim and counter claim between Turkey and the Greek-EU alliance continue. Von der Leyen has since said she will also be in attendance.

Hungary has implemented similar measures preventing migrants without visas into transit zones on its southern border, citing a link between the coronavirus and migration that is yet to be proven. 

Meanwhile, Boyko Borissov, the prime minister of Bulgaria, which also shares a land border with Turkey, was due to hold talks in Ankara on Monday evening with Erdogan.

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