BRUSSELS (Reuters) – A deal between the European Union and Turkey meant to curb the flow of migrants into Europe in return for financial and political rewards could unravel within months because neither side looks able to deliver on its commitments.

Turkish Prime Minister Ahmet Davutoglu and European Council President Donald Tusk wore relieved smiles on Friday as they sealed a pact for Ankara to take back all migrants and refugees who cross to Greece in exchange for more money, faster visa-free travel for Turks and slightly accelerated EU membership talks.

But for Turkey to halt the flow of migrants to Europe will require a major redeployment of its security apparatus to shut down a lucrative people-smuggling business at a time when President Tayyip Erdogan has more pressing priorities.

With impeccable timing, Turkish authorities announced they had detained 3,000 would-be migrants on Friday, but Greek officials say Ankara has done little to stop the flow since November, when the EU and Turkey made a first deal.

Yet Erdogan is more focused on extending his presidential powers, fighting Kurdish militants and preventing spillover from Syria’s civil war.

For Greece to be able to process and send back those migrants who continue to reach its islands would require a transformation of its threadbare asylum and justice systems with scant resources and uncertain EU assistance. The European Court of Human rights considers Athens’ system so poor that it ruled that sending migrants back there from other European countries was inhumane.

Yet the new arrangements are supposed to start from Sunday, with the first returns set for April 4. One EU diplomat said that was like expecting Greece to turn itself into the Netherlands over a weekend.

For the EU to resettle, as promised, thousands of legal Syrian refugees directly from Turkey – one for each Syrian returned from the Greek islands – will require most member states to take in more refugees than they have been willing to share out so far. In the current climate of anti-immigration populism in many countries, that may be a tall order.

The joint statement did not spell out who would return potentially unwilling migrants from Greece to Turkey, a task that may fall to the EU’s Frontex border agency under the critical gaze of the media and humanitarian groups. Greek officials say they are worried it could turn violent.

Images of Afghans, Iraqis or Syrians being removed against their will could lead to an international outcry.

In a foretaste, rights group Amnesty International posted a harrowing picture of refugees cowering behind barbed wire outside the EU summit center with the slogan “Don’t trade refugees. Stop the deal!”

LOGISTICAL CHALLENGE

Greece already faces a huge logistical challenge with 43,000 migrants bottled up in the economically ravaged country since its northern neighbors shut their borders, and more continuing to arrive daily, albeit at a slower pace.

And all this is before the summer weather and calmer seas that facilitated last year’s mass influx.

For the EU to give Turks visa-free travel by the end of June also requires a leap of faith, since Ankara has so far met fewer than half of the 72 conditions. European officials stress the ball is in Turkey’s court to pass the necessary laws and change its visa regime with other, notably Muslim countries.

The EU managed to sidestep a potential stumbling block over Cyprus by agreeing to limit Turkey’s progress in snail’s pace membership negotiations to one policy area – budget – which Nicosia has not blocked.

That got around a standoff over Ankara’s refusal to open Turkish ports and airports to Cypriot traffic. A late addition to the agreement also reminds Ankara of its commitments to the Turkey-EU customs union under which it should open its ports.

If both sides are lucky, the vexed Cyprus issue may not impinge on the migration deal for months, leaving time for peace talks now under way that may lead to the reunification of the east Mediterranean island after more than 40 years of division.

EU leaders desperate to stop the chaotic migration flow were willing to suspend their disbelief and swallow legal qualms – at least in public – because they had no better alternative.

But they have few illusions.

German Chancellor Angela Merkel, the deal’s co-architect, said there were bound to be setbacks and big legal challenges but she hoped the deal had “irreversible momentum”.

Tusk, who chaired the summit, said the deal was the best the EU could do for now. “A piece of something is better than a piece of nothing,” he said.

“There are many bits of this deal that clearly don’t add up,” a senior EU official acknowledged. “Much of the details will be left to be worked out at lower level later on.”

The optimistic version, voiced by Dutch Foreign Minister Bert Koenders, is that some “intelligent synchronization” can be found between the Cyprus peace process and Turkey’s migration deal. Critics say that is just EU wishful thinking.

‘NO BETTER PLAN’

Some experts believe Turkish leaders don’t expect the EU to keep its word on visas, refugee resettlement or the membership talks and are planning to turn a predictable failure to domestic political advantage.

“Davutoglu and Erdogan know perfectly well that neither side will deliver,” said Michael Leigh, senior fellow at the German Marshall Fund think-tank and a former director-general of the EU’s enlargement department.

“What Erdogan wants is a constitutional power change … so he will present it at the right moment as a European betrayal and call a vote to get more powers,” Leigh said.

At most, he said, the EU could fulfill the financial part of the bargain if Germany pays the lion’s share of the extra 3 billion euros ($3.4 billion) Ankara was promised to support Syrian refugees in Turkey.

Sidelined by Merkel when she drafted the outline deal with Davutoglu last week, French President Francois Hollande made clear he would hold Turkey to meeting EU visa standards in full.

“Visas can only be liberalized if all the conditions are met and I remind you there are 72 of them,” Hollande told reporters. A French diplomat said Turkey had only fulfilled 10 benchmarks fully so far and another 26 were under way.

EU diplomats are skeptical that Ankara will be able to meet all the required benchmarks in time, but such is the urgent need to get the migration crisis under control that they would rather clinch a deal now and deal with shortcomings later.

“It’s difficult but everyone has an interest in trying to make this work and no one has a better plan,” a senior EU diplomat said.

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(Writing by Paul Taylor; Editing by Pravin Char)