All week Nato has been holding military exercises with Ukrainian troops in the west of the country as the conflict in the east of Ukraine continues.

Most of the fighting between rebel forces, backed by Russia, and the Ukrainian military is concentrated to the north and west of the city of Donetsk.

The BBC's Tom Burridge has been to Donetsk's former airport, which has been devastated by the fighting, and where there are fierce exchanges almost every day.