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CNN  — 

Ukraine’s military on Sunday said it had destroyed one of Russia’s newest and most advanced fighter jets in a drone strike on a military base deep inside Russia.

The Sukhoi Su-57 fighter, nicknamed the “Felon” by NATO, was struck on the tarmac of an airbase in the Astrakhan region, almost 600 kilometers (372 miles) behind the front lines of fighting in Russia’s invasion of Ukraine, according to Ukraine’s defense intelligence agency (GUR).

The agency posted satellite pictures in a post on its Telegram channel to support its claim, writing, “The images show that on June 7, Su-57 was still intact, but on June 8, craters from the explosion and distinctive fire spots emerged near it as a result of the fire damage.”

The Su-57 is a supersonic, twin-engine, fifth-generation stealth fighter jet and was seen as Moscow’s answer to Western stealth jets like the US Air Force’s F-22 Raptor.

But its development, which began in 2002, according to the US military, has been slow, and an Su-57 crashed during a 2019 test flight.

The Russian military received its first Su-57 in 2020, according to a report by the state-run TASS news agency, which said the jet was earlier “tested” in combat conditions in Syria in 2018.

The Ukrainian Telegram post noted the Su-57’s ability to carry Kh-59 and Kh-69 cruise missiles, which the jet could launch against Ukraine from the safety of Russian airspace.

While experts have expressed doubts on the Su-57’s capabilities compared to the F-22, Russian officials have praised its role in attacks on Ukraine.

In a 2022 TASS report, then Defense Minister Sergey Shoigu said the Su-57 “has shown itself brilliantly.”

“The aircraft has a very high degree of protection against various air defense systems, has protection against missiles … Most importantly, it has very powerful weapons. We also tried and tested these weapons, they work brilliantly,” Shoigu said at the time.

The exact number of combat-ready Su-57s available to Russia’s air force is unclear. Flight Global’s “World Air Forces 2024” directory lists 14 Su-57s as active and another 62 as on order.

“The Russian Aerospace Forces currently have only a limited number of these combat aircraft in service,” the GUR Telegram post said.

TASS reported in 2022 that Russian forces will receive a total of 22 Su-57s by the end of this year.

If the reports of the Ukrainian drone strike deep inside Russia prove true, it marks another success of Kyiv’s low-cost drones taking out high-value Russian assets. The price of an Su-57 is estimated to be $35 million to $54 million, according to the Foreign Policy Research Institute.

Drone strikes have become an increasing problem for Moscow. Other Ukrainian drones have been used to sink or severely damage Russian warships in the Black Sea, and tanks and armored vehicles have fallen prey to drones on the battlefield.

The attack would also bring new worries for Russia in protecting bases far back from the battlefield.

“This is a really a trend that the Russians are worried about,” said CNN contributor Jill Dougherty, the network’s former Moscow bureau chief.

“The Ukrainians are attacking more and more inside Russia and taking the battle to them,” Dougherty said.

After reports of the strike surfaced, Russian military bloggers criticized the military for not building hangars to protect the Su-57s, noting that protective hangars could be constructed at every air base for the price of one Su-57, according to the Institute for the Study of War.