BRUSSELS (Reuters) - Amid all the arguments about the feasibility, legality and morality of the European Union's migrant deal with Turkey, one positive result, say EU officials and diplomats, is that at least it hasn't wrecked the Cyprus peace process.
But it remains to be seen whether that can, as one EU senior official hopes, "turn a threat into an opportunity" to use intensified contacts between Nicosia and Ankara to secure reunification of the island's Greek-speaking EU member state and a breakaway, Turkey-backed north after four decades of division.
The migrant deal is intended to halt illegal migration flows to Europe in return for financial and political rewards for Ankara. European Council head Donald Tusk, who chaired Friday's EU-Turkey summit, said a compromise accepted by Turkish Prime Minister Ahmet Davutoglu to avoid a Cypriot veto on the migrant deal was a "very promising signal for the future".
Rapprochement between the Greek- and Turkish-speaking halves of the island in the past year have raised hopes of a deal that could bring a rare bright spot of peace in a troubled region.
Last week, however, Turkey's demand to open five negotiating topics, known as chapters, in long-stalled talks on its distant membership prospects with the EU set Ankara -- along with German Chancellor Angela Merkel and other EU leaders keen for a deal -- on a collision course with Cypriot President Nicos Anastasiades.
Cyprus had blocked the five chapters for years over Turkey's failure to recognize its right to access Turkish ports as part of a customs union deal with the entire EU and vowed to veto any deal it disliked. In the end, in return for taking back migrants from Greek islands, Turkey settled for - among other benefits - opening just one chapter, which Cyprus had not frozen.
"We really dodged a bullet on this one," said James Ker-Lindsay of the London School of Economics, who has advised U.N. negotiators seeking a settlement on Cyprus. "It could have got very, very nasty if Turkey had decided to dig its heels in."
Turkey's EU affairs minister had warned Europeans not to let Cypriot "caprice" block a deal and EU officials acknowledged that Merkel and other leaders, under huge pressure at home over the arrival of migrants from Turkey, were impatient with Cyprus.
In the end, however, Davutoglu accepted the deal and told a news conference he was "optimistic" about relations with the EU.
Anastasiades voiced "full satisfaction" and said he would support Turkey's EU accession talks if it meets his conditions.
Turkish Cypriot leader Mustafa Akinci tweeted: "The EU-Turkey deal reached as a result of the compromise culture is a positive outcome which is also helpful for the Cyprus negotiations."
Officials involved in the talks said Tusk had been anxious to broker a compromise to avoid a domestic backlash against Anastasiades at parliamentary elections on May 22 that might imperil his cooperation with Akinci, who took office a year ago.
"This may be the last generation of politicians in Cyprus who still want a settlement," a senior EU official said of the rapport between the two, who are both in their late 60s.
"To wreck Anastasiades is to derail the settlement process."
Tusk got a personal taste of the issue on a visit to Nicosia and Ankara before the summit. Leaving Cyprus on a Belgian air force NATO plane for NATO member Turkey, Tusk had to fly via Greece due to Turkish refusal to recognize the island state.
Turkey, backed by Merkel, sprang its offer to take back migrants - in return for, among other things, five new accession chapters - on unsuspecting EU leaders at a special summit two weeks ago. Anastasiades then came under heavy pressure to agree.
"Five (EU) leaders in a room shouting at him to give ground wasn't going to work and could derail the peace process," an EU official said of efforts to convince Anastasiades on March 7.
Diplomats involved in the negotiations said Turkey appeared to believe it had sufficient leverage over the EU on migration to overcome the Cypriot block on accession chapters. In the end, however, EU negotiators closed ranks to avoid a Cypriot veto.
Yet despite the deterrent effect hoped for from the accord, migrants have arrived on Greek islands since the deportation scheme came into force on Sunday, raising the prospect of more negotiations between the EU and Turkey. That may mean further discussion with Cyprus that cuts across the peace talks, despite Anastasiades' insistence they are "two distinct processes".
Ker-Lindsay at LSE said the interplay of the EU migration issue with U.N.-mediated efforts for a reunification deal could still cause "serious problems", though he said all sides, including Turkey, appeared keen on a settlement for the island.
Tusk urged Davutoglu to see a possible virtuous circle: "A comprehensive settlement to the Cyprus problem will be beneficial to the wider security and stability of the region -- and in particular to the strategic relationship between Turkey and the EU."
Editing by Gareth Jones