LESBOS, Greece (AP) " The waters off the Greek island of Lesbos once echoed with the shrieks of people drowning as they struggled to reach Europe, and the thrumming of rescue helicopters.
A coastguard patrol Friday encountered nothing more alarming than a few fishing boats.
A deal between Turkey and the European Union stemmed the flow of migrants who used to come ashore here by the hundreds every day " or died trying to make the crossing from Turkey in flimsy boats.
One year later, that agreement appears at risk amid deteriorating EU-Turkish relations, raising fears that Lesbos once again will become the scene of a humanitarian catastrophe.
The year-old deal enacted hinges on Turkey taking back people detected crossing the Aegean Sea by Greek, EU and NATO ships. But Turkey's recent diplomatic fight with EU member countries over a referendum on expanding the power of the Turkish president could scuttle it.
Furious that Germany and the Netherlands barred his ministers from campaigning in their Turkish immigrant communities, President Recep Tayyip Erdogan said Thursday the EU could "forget about" the deal, stepping up similar threats made in recent months.
Turkey's Interior Minister Suleyman Soylu also threatened during a campaign meeting to let thousands of refugees make their way into Europe, Milliyet newspaper reported.
"If you like, we could open the way for 15,000 refugees that we are not sending each month, so that you are shocked," Soylu said.
Weeks before the deal took effect, a series of Balkan countries on the migration trail north from Greece to Europe's prosperous heartland sealed their borders to migrants.
If Turkey breaks the agreement " and thousands of asylum-seekers reach the Greek islands " they would be trapped in the financially struggling country, pushing its rickety reception and housing system to collapse.
"We all hope the deal will not be broken, so that we don't find ourselves in a situation like in the past," Captain Nikos Passades, the head of the Lesbos coast guard, told The Associated Press during a patrol on Friday.
A million people crossed the straits between Turkey and Greece's eastern Aegean islands in the year before March 20, 2016, when the deal took effect. Hundreds drowned. About half of those who made it landed on Lesbos.
Since the agreement, about 25,000 have arrived, fewer than in an average week at the peak of the migrant crisis in late 2015.
Europe's response has been muted as officials weigh whether Erdogan's threats should be taken seriously or whether they're intended to galvanize voters at home ahead of the April 16 referendum.
EU migration commissioner Dimitris Avramopoulos, a Greek, voiced hope Friday that Ankara would not go beyond rhetoric.
"It is imperative that the agreements continue to be implemented " and to remove any link with the recent spat between Turkey and various European countries," Avramopoulos told Skai TV, a Greek private broadcaster.
Middlesex University International Politics Professor Brad Blitz said the deal appears fragile and its collapse would harm a wider EU agenda for similar agreements with African states.
"The problem is that flows can increase quickly," Blitz said. "Instability, especially in eastern Turkey, could see refugees moved on and out into Greece."
Under the deal, which has been criticized as inhumane by humanitarian organizations, migrants who get across the water are interned on the islands. They face forcible return to Turkey, unless they can satisfy Greek authorities that they merit asylum in Greece.
This is where the EU-Turkey agreement faces a second, legal challenge. Two Syrian refugees who reached Lesbos in July 2016 have appealed to Greece's supreme court to block their forcible return to Turkey, with a decision expected after mid-April.
The case, the first of its kind, could have sweeping implications for the way the deal is enforced. The court is being asked to examine whether Greece's system of hearing asylum appeals is constitutional. If the system is found unlawful, new procedures would have to be adopted.
"The decision will judge, to a great extent, how Greece implements the deal," Markos Papaconstantis, a legal adviser to Greece's migration ministry, said.
Some 14,000 people are now stuck on the islands, although several thousand who won asylum have moved on to the mainland, joining another 48,000 who are awaiting relocation to other EU countries. It's already a slow process, one likely to be completely derailed by another wave of mass arrivals.
Nassem Mujada, 23, who is from Afghanistan and arrived on Lesbos six months ago, said he wants to head on to Athens.
"When we go to the camp, we feel like we're in Afghanistan. There's fighting, fires, and the police also hit people," he said. "Why don't they let us leave this island? I just want to ask them. ... But no one here answers our questions."
Paphitis reported from Athens. Thanassis Stavrakis in Lesbos, Derek Gatopoulos and Fanis Karabadzakis in Athens and Suzan Fraser in Ankara contributed to this report.
This story has been automatically published from the Associated Press wire which uses US spellings