European Union leaders welcomed Turkey's offer on Monday to take back all migrants who cross into Europe from its soil and agreed in principle to Ankara's demands for more money, faster EU membership talks and quicker visa-free travel in return.
However, key details remained to be worked out and the 28 leaders ordered more work by officials with a view to reaching an ambitious package deal with Turkey at their next scheduled summit, on March 17-18.
German Chancellor Angela Merkel and British Prime Minister David Cameron among others hailed the surprise Turkish proposal at an emergency summit in Brussels as a potential breakthrough in Europe's politically toxic migration crisis.
More than a million people fleeing war and poverty in the Middle East and beyond have flooded into the EU since early 2015, most making the perilous sea crossing from Turkey to Greece, then heading north through the Balkans to Germany.
Turkish Prime Minister Ahmet Davutoglu told EU leaders that Ankara was willing to take back all migrants who enter Europe from Turkey in future, including Syrian refugees, as well as those intercepted in its territorial waters.
"With this game-changing position in fact our objective is to discourage illegal migration, to prevent human smugglers, to help people who want to come to Europe through encouraging legal migration in a disciplined and regular manner," he told a news conference after the summit.