The Russian Aerospace Forces, or VKS, continues to burn through the life span of its fighter aircraft in the war against Ukraine. After two years of air war, its total force is slightly less than 75% of its prewar strength.

The VKS has directly lost approximately 16 fighters over the past eight months. However, this does not account for the imputed losses, which arise from an aircraft accruing more flight hours than planned, reducing its overall life. Based on updated information, the VKS is on track to suffer approximately 60 imputed aircraft losses this year from overuse. That is equivalent to losing 26 new airframes. Meanwhile the VKS currently procures only about 20 total Su-30, Su-34 and Su-35 aircraft per year.

The air war has mostly maintained a steady state since mid-2023, with the exception of February 2024, when the VKS flew approximately 150 sorties per day in support of the Avdiivka offensive. Given that Russia also has been using longer-range glide bombs and devoted more aircraft to air-to-ground roles, the average sortie duration has also likely decreased, reducing the accelerated aging. Still, slightly more than half of the VKS’ tactical airframes are more than 30 years old; these have far fewer flight hours left.

The accelerated aging may be shaping Russia’s combat operations. The majority of VKS fighters operating (and lost) over Ukraine are the newer Su-30, Su-34 and Su-35 aircraft with occasional reported sightings of Su-25s.

The older MiG-31s and Su-27s have been relegated to supporting hypersonic Kinzhal strikes and air patrol at a distance. With an estimated average remaining airframe life of less than 20% and 35% respectively, these older aircraft can be used for this war, but likely have insufficient life to support Russia’s potential future invasions.

Russia’s air-to-air warfare MiG-29s are totally absent, even from air-patrol missions. Given their age, these aircraft may be either unserviceable or are being kept in reserve for a final mission. Regardless, whether due to lack of upgrades, survivability or age, these are effectively paper airplanes.

The Su-24s, on the other hand, were used extensively in the invasion of Ukraine. But there have been no reports of Su-24 losses thus far in 2024. How much are they still flying? These aircraft are old; the newest models were manufactured in 1993. The VKS may have chosen not to configure them for their new FAB-1500 glide bombs, which would also hint at the fact that the Su-24s may be reaching the end of their useful lives.

Ukraine, which is short on air defense munitions, has a few options to accelerate Russian air losses. Attacking air bases would likely reduce VKS sortie rates by more than 20% by disrupting operations and forcing the VKS to fly from more distant bases. The greatest opportunity remains the effect of forthcoming F-16 jets (and possible Gripens) to divert VKS sorties from ground-attack to air-to-air efforts.

Regardless, more air defense munitions and fighters will be critical to Ukrainian success. Russia is relying on only about 300 combined Su-30, Su-34 and Su-35 aircraft for its operations over Ukraine, including delivering the hugely destructive glide bombs. From a strategic perspective, shooting down these newest VKS aircraft imposes a larger cost to Russia and would have the greatest overall impact on the VKS’ ability to perform strikes. It would also improve the odds of survival of the 45 F-16s allies promised to Ukraine.

The VKS has fewer than 650 tactical aircraft when accounting for end-of-life aircraft; it has even less when accounting for accelerated usage. But these numbers are unlikely to change its behavior, based on Russia’s exhibited willingness to accept high losses even for trivial gains.

In comparison, NATO has roughly 800 fifth-generation aircraft, with another 100 or more arriving every year. This is more than sufficient to counter the VKS in the air and conduct targeted ground strikes, especially given the poor performance of Russian surface-to-air missiles in Ukraine.

To be sure, NATO should expand its production of air-to-air and surface-to-air munitions to deter further Russian aggression and support Ukraine. But with the VKS currently shrinking, the alliance can afford to donate more munitions to Ukraine now without worrying about its immediate strategic reserves.

Michael Bohnert is an engineer at the think tank Rand. He previously worked as an engineer for the U.S. Navy and the Naval Nuclear Laboratory.

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