Joint Russian-Serbian BARS (Brotherhood of Aviators of Russia and Serbia) tactical flight drills have kicked off in the Russian central city of Lipetsk, Russia’s Defense Ministry said on Monday.

The drills are carried out in accordance with the international military cooperation plan and will conclude at the end of next week, according to the ministry.

The joint crews of fighter and army aviation participate in the drills using Russian Air Force’s MiG-29 and Mi-8 helicopters. In total, some 20 aircraft would take part in the exercises conducted both during night and day.

Moscow and Belgrade actively cooperate in the military sphere. The first joint Russian-Serbian flight drills were held at the Ashuluk range of Russia’s Astrakhan Region in October, 2015.