ZAGREB, Croatia (AP) -- U.S. Vice President Joe Biden is attending a summit of southeast European leaders on Wednesday that focuses on tensions and security concerns over a surge of asylum-seekers and migrants crossing the region.
Biden's trip comes amid a debate in the U.S. about whether to admit Syrian refugees following the Islamic State group's attack in Paris.
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.
The refugee crisis is stoking tensions among the countries on the so-called Balkan migrant corridor — Greece, Macedonia, Serbia, Croatia and Slovenia.
The stakes were further raised amid fears that the masses of refugees crossing into Europe mostly from the Middle East could be infiltrated by Islamic extremists. At least two of the militants involved in the Nov. 13 Paris attacks had passed through Greece, apparently posing as migrants.
"The summit comes at the right time as security concerns have increased due to recent events," Slovenian President Borut Pahor said before the meetings. "Politicians now have the responsibility to take measures for securing peace and security in the region."
Managing the massive flow has proved a major political and security challenge for the countries on the migrant route. Inability to agree on a common European Union policy toward the surge has further hindered the right response.
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.
Biden will also meet in Zagreb with European Council President Donald Tusk to discuss the migration crisis, the fight against extremism, the Russia-Ukraine conflict, energy and trade. He also attended bilateral meetings with Croatian and other leaders to discuss the response to the refugee crisis, energy and economic ties.
The Balkan nations said earlier this month they would only let in people fleeing conflicts, such as in Syria, Iraq and Afghanistan, and not those who are considered economic migrants.