The Latest: EU president warns deal with Turkey won't solve migrant crisis overnight

The latest on the mass movement of asylum-seekers and others seeking refuge in Europe. All times local:

2:50 p.m.

EU President Donald Tusk is warning that any deal with Turkey at a summit in Brussels will not solve the migrant issue overnight.

Walking into the EU-Turkey meeting of government leaders Sunday, Tusk said that beyond getting a deal with Ankara, the most important issue "is our responsibility and duty to protect our external borders. We cannot outsource this obligation to any third country."

At the emergency summit, EU leaders will look to offer Turkey 3 billion euros ($3.2 billion), an easing of visa restrictions and the fast-tracking of its EU membership process in return for tightening border security and taking back some migrants who don't qualify for asylum.

Tusk said that if the migrant crisis cannot be contained, the continent's vaunted Schengen system of borderless travel could collapse. "I will repeat this again: without control on our external borders, Schengen will become history," he said.