European Union leaders are lauding it as a breakthrough; Turkish Prime Minister Ahmet Davutoglu says it's bold; but it is still too early to say whether an in-principle agreement thrashed out between EU and Turkish leaders announced early Tuesday is the answer to all of Europe's refugee woes.

The deal could see thousands of migrants coming to Europe returned to Turkey. In exchange, the EU would accept thousands of Syrian refugees, bringing them in by safe routes and keeping them out of dangerous boats and out of the hands of traffickers.

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THE BOTTOM LINE

Turkey would take back migrants who are picked up in the Aegean Sea that separates Turkey from Europe or who have arrived in Greece but have not applied for asylum there. Based on a "one-for-one" principle, European nations would accept migrants from Turkey who are likely to obtain asylum. That probably means only Syrians.

This draft deal is unlikely to have any perceptible impact on migrant movements across the Mediterranean to Italy.

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WHAT IT MEANS

The Europeans hope it will bring order to the chaotic migrant movements of recent months and end the unilateral tightening of borders instigated by some countries. It could stop people making the dangerous sea crossing to Greece. Almost 450 have already died or gone missing this year alone. It could deprive traffickers and smugglers of revenue by providing safe passage for migrants. Pressure would ease on Greece, where tens of thousands are currently stranded and thousands more arrive every day hoping to move north to preferred destinations in Germany or Scandinavia.

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THE COSTS FOR EUROPE

A deal will not come cheap. The EU had already promised Turkey 3 billion euros ($3.3 billion), fast-track EU membership talks and the swift easing of visa rules for Turkish citizens. Turkey upped the ante on Monday, demanding twice the money, promising that funds will go only to Syrian refugees, not Turks. By the time the preliminary deal was announced, figures had melted away and Davutoglu spoke only of "additional funding." Turkey now wants visa rules eased by the end of June, six months ahead of schedule. New steps must also be taken to speed up its membership process.

Europe would also pick up the tab for transporting refugees between the EU and Turkey. On top of that, Turkey has revived a demand for the Europeans to back a "safe area" in northern Syria so that people there would not flee in the first place. The EU has previously said that any initiative to create such a zone would have to come from the United Nations.

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THE COSTS TO TURKEY

Turkey is home to an estimated 2.7 million refugees, most having fled the conflict in Syria. Rights group say few are sheltered by the government and that the overwhelming majority are staying with Turkish citizens or living rough. The plan would see more migrants flood into a country that hosts more refugees than any other place in the world. They would have to be registered, housed and probably in many cases sent back to their home countries, a process that could take several months or even years. While that implies significant costs, the EU will help foot the bill. Additionally, Turkey would station immigration and liaison officers in the Greek islands to speed up the process of taking people back.

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NEXT STEPS

The summit chairman, EU Council President Donald Tusk, has been tasked with chaperoning a deal through in coming days. He's already spent the last week in Turkey and the Balkans talking to leaders as Europe's refugee emergency deepened. The aim is to seal the deal at the next EU summit in Brussels starting March 17. It's the third time in a month that European leaders have met to tackle an issue that has divided them and so far proved to be an intractable problem. Getting that 3 billion-euro refugee fund was tough enough. Europe desperately needs Turkey's help. Tusk's challenge in the week ahead will be to establish how much EU nations are willing to pay.