U.S. administration officials say security and humanitarian constraints are concerns for the European leaders, with up to 5,000 migrants reaching Europe each day over the so-called Balkan migrant route. Slovenia wants to limit the flow on the Balkans route so the country can re-establish a normal functioning of the passport-free Schengen system of border controls. While it has recently started to erect a razor wire fence along the border with Croatia to aid these efforts, an agreement with its southern neighbor should be the main priority, Pahor said.