FILE - Hungarian soldiers work on a fence that is being built at the border with Croatia, near the village of Beremend, Hungary, on Sept. 22, 2015. (AP Photo/Petr David Josek, File)
FILE - A migrant girl walks behind a barbed wire fence at a makeshift camp in Horgos, Serbia, seen from the Hungarian side of the border, on Sept. 30, 2016. (AP Photo/Vadim Ghirda, File)
FILE - Syrian refugees cross into Hungary underneath the border fence on the Hungarian - Serbian border near Roszke, Hungary on Aug. 26, 2015. (AP Photo/Bela Szandelszky, File)
FILE - Hungarian soldiers put up razor wire on top of a fence on the border with Serbia, in Asotthalom, Hungary, on Aug. 31, 2015. (AP Photo/Darko Bandic, File)
FILE - A man walks by an anti-migration billboard from the Hungarian government, on a street in Budapest, Hungary, April 7, 2018. (AP Photo/Darko Vojinovic, File)
FILE - Hungarian soldiers work on a fence that is being built at the border with Croatia, near the village of Beremend, Hungary, on Sept. 22, 2015. (AP Photo/Petr David Josek, File)
FILE - Hungarian soldiers build a fence on the Hungarian - Serbian border near Asotthalom, Hungary on Aug. 10, 2015, as the flow of migrants continues to hit Hungary's southern borders. (AP Photo/Bela Szandelszky, File)
FILE - A migrant from Afghanistan holds on to a fence after crossing to Hungary from Serbia in Roszke, Hungary, on Sept. 30, 2016. (AP Photo/Vadim Ghirda, File)
FILE - Migrants arrive at the Hungarian border fence between Serbia and Hungary near Roszke, southern Hungary, on Sept. 13, 2015. (AP Photo/Matthias Schrader, File)