Last week, Ukraine’s parliament passed a new law restricting the teaching of Russian and other minority languages in its schools, in a move that could aggravate social tensions. In an email interview, Nicolai Petro explains the impact of the law and what can be expected in Ukraine’s relations with its neighbors.

Serbia’s short-lived withdrawal of its diplomats from Macedonia in late August, following a narrowly avoided regional trade war, brought the timeworn phrase “Balkan tensions” back into the news. Both events are a sign of the difficulties in integrating Balkan countries into the EU—and with one another.