Ukraine has been flying shockingly deep inside Russia because Russian air defenses are so degraded, military expert says

• Ukraine has been able to fly surprisingly far into Russia unimpeded, a military expert says.
• George Barros told Business Insider that Russia's air defenses had been stretched for multiple reasons.
• Ukraine has destroyed some Russian systems and is targeting more, straining Russia's resources.

Ukraine has been able to strike unusually deep inside Russia because Russian air defenses have been stretched, a warfare expert told Business Insider.

George Barros, a Russia expert for the Institute for the Study of War in the US, said many of Ukraine's drones were able to penetrate past the point where Russian air defenses should be able to stop them.

"We've seen numerous times where the Ukrainians have penetrated Russian air defenses and then flown aircraft that the Ukrainians really have no right to fly as deep as they have into Russia," he said.

"Russian air defenses should have very easily taken them out."

Russia's air defenses have been formidable opponents for Ukraine as it fights back against invasion . They've downed Ukrainian jets and missiles, largely denying Ukraine access to Russia's airspace.

Ukraine's defenses have proved their worth too, holding back Russia's much larger air force — something air-warfare experts praise as a remarkable achievement given Ukraine's disadvantage in the air.

That has created a situation of mutual air denial, in which both sides are mostly limited to using their own aircraft in their own territory.

But Barros said Russia's defenses had been "stretched," giving Ukraine new opportunities.

He said Russia "neglected to protect the areas" that aren't right beside Ukraine. Then, starting in spring 2024, Ukraine was able to pick off Russia's defenses "in a very deliberate manner," he added.

Many of Russia's air-defense systems have been damaged and destroyed by Ukraine, and Ukraine is now targeting some defenses that it couldn't previously reach. Russia has to figure out how to protect them.

Barros said Russia "arrayed their air-defense assets to protect the areas under air threat."

If Ukraine gets past that, its forces "enter this area within interior Russia which is not adequately protected," he added.

He said that an example was Ukraine hitting the Russian region of Tatarstan, 807 miles from the border with Ukraine. The strike in April used what experts said seemed to be a light aircraft that had been converted to fly remotely.

"That incident was very demonstrative and indicative that the Russians have likely arrayed their air-defense assets in such a way that they have good coverage in the immediate theater around Ukraine. But beyond there, they don't have it," Barros said.

Ukraine recently got new permission from allies to hit within Russia using donated weapons, meaning Russia has more sites it needs to consider defending.

And the ISW said this month that Ukraine's escalating drone attacks on Russian military and oil facilities, sometimes hundreds of miles inside Russia , had also stretched Russia's capabilities.

The ISW said such strikes "continue to pressure Russia's air defense umbrella and force the Russian military command to prioritize allocating limited air defense assets to cover what it deems to be high-value targets."

Ukraine has destroyed many Russian air-defense systems, particularly in Crimea, the Ukrainian peninsula that Russia annexed in 2014.

The ISW said last month that Ukraine's attacks on Russia's defenses there could stop Russia from using Crimea as a military staging ground .

While this level of breakthrough is good news for Ukraine, it's unlikely to change the course of the war by itself.

For that, Ukraine would need to further degrade Russia's defenses and get more of its own defenses from allies, as its arsenal is more stretched than Russia's.

Combined with stronger air power — such as the Western F-16s which began to arrive at the end of July — then the advantages could grow.

Many warfare experts have said this war has largely become an air-defense war, making both countries desperate to keep their arsenals strong.