Russia's Air Force announced on Wednesday the launch of a tactical exercise involving long-range aviation in "northern latitudes" to rehearse interoperability in air patrol missions.

"The active phase of the tactical exercise has started under the command of long-range aviation commander Maj. Gen. Pavel Androsov," the Armed Forces command said in a press release.

It did not say exactly where the exercise was being conducted or whether it was in Russia or outside its borders.

The drill, including one heavy-bomber regiment, will practice midair refueling, flights over uncharted terrain and in difficult weather conditions, as well as landings on off-base, alternate airfields.

Over 20 Tu-95 (Bear) strategic bombers and Il-78 (Midas) four-engine aerial refueling tankers will participate in the exercise.

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Last August, Russia resumed long-range patrol missions of strategic bombers, which were suspended in 1992 following the breakup of the Soviet Union.

It said air patrol areas would include zones of commercial shipping and economic activity and would be conducted on a permanent basis.

NATO has requested that Russia give it advanced warning of military exercises.