The Russian Air Force has started a series of military exercises in the country's central and western districts near its border with Ukraine.
The exercise involves more than 100 military aircraft, including Su-27 and MiG-31 fighters, Su-34 bomber, Mi-8, Mi-24 and Mi-28N attack helicopters.
The exercises, which will begin today, will be undertaken in two phases until 8 August.
Russian Air Force spokesman Igor Klimov told Interfax news agency: "The aircraft will be testing weapons on land and air targets on new ranges, and will be conducting real and electronic launches of anti-aircraft missiles in Ashuluk (Astrakhan region in southern Russia) which is specifically designed to aide the coordination between aviation and anti-missile defence."
The exercises represent the first in a series aimed at enhancing coordination among the Russian armed forces.
During the first phase, the aircraft will relocate from the northern airfields of the Western Military District to the Central Military District. The second phase will involve the aircraft assigned to the southern airfields, RIA Novosti reported.
The drills come at a time when pro-Russian rebels are fighting Ukraine's troops in Donetsk and Luhansk regions.
The rebels have shot down another Ukrainian Su-25 fighter aircraft on Sunday.
A militia spokesman told RIA Novosi: "It (plane) is lying between the towns of Yenakiyevo and Makiivka (Donetsk region)."
Ukraine has also confirmed the aircraft crash and said the search for the pilot is underway.
Pro-Russian rebels are reported to have brought down several Ukrainian aircraft, including three Sukhoi Su-25 fighters and an Antonov An-26 transport plane, in the eastern region of the country since May.
A Malaysia Airlines passenger flight, MH17, crashed last month after it was hit by a missile in the disputed region.
Image: Pro-Russia rebels have shot down another Ukrainian Su-25 fighter aircraft on Sunday. Photo: public domain.