"Even Moscow is no longer safe!" What used to be warmongering among many patriotic Russian bloggers and activists online is now turning into anger and uncertainty.

Engels and Dyagilevo — the names of the two airfields rocked by powerful explosions on December 5 — are the new code words on social media for a new sense of bewilderment in Russia. They are the largest bases for long-range bombers in the country, which President Vladimir Putin sees as a superpower. But they also represent the first time in more than nine months of war that Ukrainian combat drones have hit strategic targets far in Russia's hinterland.

The Ukrainian strike could not be more symbolic, not least of all because the bombers that take off from these airbases are regularly armed with dozens of cruise missiles intended for civilian targets in Ukraine, mainly critical infrastructure that provides electricity and heat to the population.

Confusion over Ukrainian airstrikes

Even though Ukraine, in contrast to Russia, has so far only taken aim at military targets in the neighboring country, these strikes have highlighted that the Russian capital is now actually within range as well. Both up to well over 600 kilometers (373 miles) away, the airfields are actually farther from the Ukrainian border than the Kremlin, which has surprised experts.

"It's astonishing that Russian air defenses have not reacted — it's possible that the Russians still don't expect such attacks in the depths of Russian territory," Bundeswehr University political scientist Frank Sauer told DW.

The Russian Defense Ministry claims to have shot down the drones, with two bombers allegedly damaged by their debris. However, several videos that appeared online from private surveillance cameras near the airfield in Engels seem to disprove this. The early morning footage clearly shows that there was no explosion in the sky — only a strong detonation on the ground.

Mysterious drones

Days later, military experts are still puzzling over exactly what was used to hit the Russian airfields. The Defense Ministry in Moscow has referenced a "Soviet-designed drone." Experts suggest it could be a modernized version of the Tu-141, a 1970s reconnaissance drone from the USSR, laden with explosives.

"The achievement here is to get the old aircraft on target accurately over the distance," Sauer said, noting that in March, shortly after Russia invaded Ukraine, a Tu-141 strayed all the way to Croatia and hit the capital, Zagreb.

Ulrike Franke, a security expert from the European Council on Foreign Relations (ECFR), also said that a Tu-141 retrofitted with state-of-the-art navigation technology could have been used. However, she remains skeptical about Moscow's claim as long as there is no footage of debris from the drone.

"It may be, of course, that Russia claims it is a Soviet drone, simply to show that the Ukrainians are incapable of developing their own drone," she said.

But building combat drones is not technological witchcraft, Franke told DW.

"It may well be that the Ukrainians have developed such a drone during the war. In this war, Ukraine is always being innovative," she said, citing Ukrainian attacks on Russian warships with water drones, as well as the use of Turkish Bayraktar drones to distract the Russian war fleet's radar systems and hit them with guided missiles from the ground.

Dozens of new drone types

The Ukrainian Ministry of Defense is keeping quiet about its drone developments. However, Defense Minister Oleksii Reznikov made it clear in a December 8 Facebook post that Kyiv places great emphasis on innovation. 

"Previously, one to two new types of drones per year received approval for our armed forces. Now we have approved seven new Ukrainian drone types within the past 30 days," he wrote.

The New York Times has cited security forces in Kyiv as saying that the newly developed combat drones, built in a public-private partnership with Ukrainian companies from the civilian sector, were used for the strikes.

Since Russia began using kamikaze drones and cruise missiles to target and destroy Ukrainian infrastructure, several private initiatives have called for donations "for acts of revenge." TV presenter Serhiy Prytula collected donations in October to fund kamikaze drones for retaliatory strikes on Russia in October, garnering nearly 10 million Euros (10.5 million USD) in just a few days, for example.

Still, Ukrainian military expert Oleg Katkov doesn't believe that Ukraine has kamikaze drones ready for mass production. Ukrainian developers have so far focused mainly on reconnaissance drones.

"On the surveillance videos from Engels, a sound can be heard that is typical of a jet engine, like one on the Tu-141," Katkov told DW. "However, I assume that new Ukrainian developments are powered by propellers."

A key role in the counteroffensive

Regardless of whether the drones are new or modernized, experts agree the strikes have more than just symbolic significance.

"The Russians will now have to redeploy their air defenses, possibly withdrawing systems from the war zone," Katkov said. "Or they could move their bombers even further into the hinterland, making future missile strikes more costly and causing more wear and tear on Russia's old Soviet bombers."

The ECFR's Franke also sees the strikes as a signal to Western partners who have so far refused to supply long-range weapons systems. Kyiv has long demanded high-tech munitions from the US, particularly for the HIMARS missile launchers that have already been delivered. Remote-launched HIMARS missiles can hit targets up to 300 kilometers away. So far, Washington has only supplied missiles with a range of 80 kilometers. But weapon systems with longer ranges play a key role in the Ukrainian counteroffensive, military experts say.

"For fear of escalation, they want to avoid Russian territory being attacked with Western systems," Franke said. "Now the Ukrainians are showing that they can handle such attacks without Western systems."

This article was originally written in German.