France has maintained border checks since the 2015 terrorist attacks. Austria first introduced controls on its borders with Slovenia and Hungary in September 2015, at the height of the refugee crisis, and has renewed them every six months since, citing migration pressures and internal security.

WARSAW - Poland introduced temporary controls on its borders with Germany and Lithuania on Monday in an effort to stem what the government says is an increasing number of undocumented migrants crossing from the north and west.