The Finnish Air Force began the largest live-fly air exercise of the autumn on Monday.
The Protective Fence 25 exercise is set to continue until Friday, and the drill will involve a total of around 50 aircraft and 1,200 personnel.
Troops from Sweden and Denmark are also participating in the exercise.
In a press release, the Finnish Air Force said that the exercise will include the use of airports in Oulu, Vaasa and Kokkola-Pietarsaari as well as Kallax Air Base in Luleå, Sweden, in addition to Finland's main operating bases.
"The objective of Protective Fence 25 is to strengthen the Finnish Air Force's defence capability and readiness," Colonel Vesa Mäntylä of Air Force Command Finland said. "During the exercise, we will conduct large-force air operations from a dispersed basing posture, in line with the Air Force’s concept of operations."
The press release added that the exercise will involve some low-level flying in the airspace over Rovaniemi, Kajaani, Kuopio, Jyväskylä and Vaasa, as well as over the Bay of Bothnia — but will end by 11pm each day.
Aside from aircraft noise, the operation will also lead to some noticeable flashes of light as well as interference with weather radars.
"During the exercise, aircraft will also employ countermeasures, including flares and chaff. Flares may appear as momentary bright lights in the sky, and chaff can cause false echoes on weather radar," the release stated.
