Ukraine shot down a Russian spy plane and airborne command center, Kyiv’s military chief said Monday, in what would be a significant blow to the Kremlin’s forces.

After reports of the incident had circulated for hours, Ukrainian army chief Valeriy Zaluzhny claimed that Ukraine’s air force destroyed two of Russia’s top-class aircraft, namely the A-50 long-range radar detection aircraft and an Il-22 air control post, both crucial to orchestrating movements on the battlefield.

“Thanks to the Air Force for the excellently planned and conducted operation in the Azov region!” Zaluzhnyi said in a post on the Telegram messaging app.

He did not specify the extent of the damage or how exactly the planes were shot down. An interactive map he shared appeared to indicate that the planes were shot down over the northern Azov Sea, which lies between the two countries.

His comment was followed by one from Ukraine’s air force in a post on X, with a caption that read “Who did this?” in English and a hush emoji, a reflection of the winking way in which Ukraine often celebrates military wins.

NBC News could not independently verify if the planes were shot down and under what circumstances.

But if the claims are true, shooting down the two planes would mark one of Ukraine’s biggest successes against Russia’s superior air power since the beginning of the war. It could also deal a blow to the Kremlin’s military operations in southern Ukraine, where Kyiv’s counteroffensive has failed to achieve clear progress on the battlefield.

Those struggles and an escalation of Russian air attacks on cities across Ukraine have dampened morale, as has a growing reluctance among Ukraine’s Western partners to commit to continue funding its fight.

Ukrainian air force spokesman Yuriy Ignat told NBC News that the loss of the A-50 was particularly significant for Russia given its powerful radar that can see for hundreds of miles.

“Russia only has a few of such powerful machines,” he added. “You can imagine what a great loss it is for them.”

He later said in a post on Facebook that the IL-22 plane may have made it back to land and was not fully destroyed, but added that the A-50 aircraft was the “priority target,” and that downing a plane like that had seemed like “an overwhelming task” for Ukraine’s air force until Monday.

The A-50 early warning and guidance aircraft is used to detect and identify airborne objects and track their location and movement, according to the Russian Defense Ministry. It described one of the IL-22 plane’s models, the IL-22M-11, as “a mobile air command post” crucial for battlefield communication. It was not clear if it was the same model of IL-22 that Ukraine claims to have shot down.

“Both types are only operational in small numbers and are critical to command and control of Russian air operations and ground-based air defense coordination,” said Justin Bronk, a senior research fellow specializing in airpower and technology at the Royal United Services Institute, or RUSI, a British military think tank. “Replacing any lost mission crews would likely be almost as problematic as replacing the aircraft themselves, since Russia has major training pipeline challenges as a result of the sustained intensity of combat operations against Ukraine over the past 23 months,” he added. 

Russia lost an IL-22 plane and its crew during the short-lived mutiny by Wagner chief Yevgeny Prigozhin last summer, Russian authorities and state media reported.

There was no immediate reaction from the Russian Defense Ministry, which did not respond to NBC News’ request for comment about the planes Monday. Kremlin spokesperson Dmitry Peskov said in his daily briefing that Moscow had no information that any Russian planes were shot down by Ukrainian forces.

Military analysts warned that it was too early to judge the significance of the incident as it remains unclear exactly how the planes were shot down and whether they were a total loss.

“We need to be careful about how much importance we attach to this,” said Christopher Tuck, an expert in conflict and security at King’s College London. “We still don’t know how they were damaged or lost: whether, for example, they were hit because of new tactics and/or capabilities employed by Ukrainian forces, whether the Russians were careless, or a combination of the two.”

The loss of the aircraft themselves would be a blow to the Russians, but not in any way decisive, he said. It adds to the existing command, control and communications problems experienced by Russian forces, he said, but the two aircraft are not in themselves pivotal.

It would be more significant, however, if the planes were lost because of new Ukrainian capabilities or tactics, Tuck added, such as pushing its Western-donated Patriot air defense systems forward.

But if Ukraine’s claims are true, it’s an “extremely embarrassing” incident for the Kremlin, no matter how the planes were lost, said Frank Ledwidge, a former British military intelligence officer and senior lecturer in war studies at England’s University of Portsmouth.

“These things should not be killed in an environment like that. They really should not,”  he said.

“I mean, we would defend these things very, very fiercely,” Ledwidge added.