The leaders of France, Germany, Italy, and Balkan states are meeting to better prevent extremists from sneaking in with migrants who are moving west across Europe.
The meeting in Paris on July 4 includes German Chancellor Angela Merkel, French President Francois Hollande, and Italian Prime Minister Matteo Renzi.
They are meeting with their counterparts from Albania, Bosnia-Herzegovina, Croatia, Kosovo, Macedonia, Montenegro, Serbia, and Slovenia, as well as Austria.
The meetings of leaders, diplomats, and finance ministers in Paris come amid questions over the EU's future after Britain voted to leave.
Balkan countries that are not already EU states worry that they will now face more hurdles to their membership bids as the bloc struggles to stay together.