"We have lost our ability to protect our borders, and in this sense, our openness is not our conscious choice, but a proof of our weakness," Tusk said at the Madrid congress of the center-right European People's Party (EPP).
He stressed that no task was more important to the European Union’s integrity today than re-establishing control over Europe's external borders, "and not in order to make Europe into an inaccessible fortress, but to effectively protect [our] values."
The EU border agency Frontex estimates that over 710,000 migrants have arrived in the European Union since the start of this year.
Several EU countries initially relaxed entry regulations for thousands of refugees camping in transit countries, like Hungary, but eventually reinstated controls with other members of the borderless Schengen Area, saying that they could not cope with the surging number of arrivals.