More than 3,000 troops are taking part in "Operation Joint Warrior" in and around Galloway Forest in Dumfriesshire.
A group of British and French paratroopers are also carrying out a parachute drop near to the Braid Fell area.
More top news
Emma Jesson brings you Saturday night's forecast
Becoming dry and bright on Saturday, turning colder. Wintry showers possible on Sunday and Monday
A look ahead at the weekend forecast for the Border region - and things are getting colder!