Ukraine launched earlier on Monday an attack on Russian military airfields in the Saratov and Ryazan regions using Soviet-made jet drones, the Russian Defense Ministry said.

According to Moscow, its air defense systems intercepted the drones, but their fragments killed three servicemen and wounded four others.

"On the morning of December 5, the Kiev regime, in order to disable Russian long-range aircraft, attempted to strike with Soviet-made jet unmanned aerial vehicles at the military airfields Dyagilevo in the Ryazan region and Engels in the Saratov region," the Defense Ministry said.

Russia said the drones were flying at low altitude when the air defenses of the Russian Aerospace Forces intercepted them.

"As a result of the fall and explosion of fragments of jet drones at Russian airfields, the hull skin of two aircraft was slightly damaged," the statement says.

By the wreckage of the Ukrainian drones, Moscow said, three Russian technical servicemen who were at the airfield were critically injured and died in the aftermath, with four more sustaining wounds of varying seriousness before they were taken to medical facilities where they received the necessary medical care.

Russia disrupted the transfer of Ukrainian troops and weapons supplied to Kiev from its allies by conducting a massive air and sea-based strike on the railroads transporting the servicemen and equipment to the combat areas, the ministry announced.

"Despite the attempts of the Kiev regime to disrupt the combat work of the Russian Long-Range Aviation by a terrorist act, today at about 15:00 [Moscow time, noon GMT] a massive strike was carried out on the military command and control system and related defense facilities, communication centers, energy and military units of Ukraine with high-precision air- and sea-based weapons," the statement added.

The goal of the strike was achieved. All 17 designated targets were hit, Moscow stressed.

The attack came days after Western media published pictures of the  Engels-2 base

It is worth noting that before the attack on Dyagilevo and Engels airfields, the German magazine Der Spiegel had published a report regarding the bases and the activity there on November 30.

It showed recent satellite images of the base and the bombers on the tarmac. It noted that the photos "show an unusual amount of movement at the Russian military airport."

Aktuelle Satellitenbilder zeigen ungewöhnlich viel Bewegung auf einem wichtigen russischen Militärflughafen. Experten sehen Engels-2 in erhöhter Alarmbereitschaft – und warnen vor einem neuen schweren Luftangriff auf die Ukraine.https://t.co/Smm3zImMz9#Ukraine #luftangriff

— DER SPIEGEL (@derspiegel) December 1, 2022

Military experts told the newspaper that Ukraine could soon be subjected to a "serious air strike", while Der Spiegel insisted that the attack appeared "imminent".

Russia conducted a similar strategic strike on Sunday, with the defense ministry saying the Russian forces destroyed an oil depot in the Kharkov region that has been supplying Ukrainian military vehicles in Kupyansk.

"An oil depot supplying fuel to military vehicles of the Ukrainian armed forces in the Kupyansk area has been destroyed near the settlement of Shevchenkove in the Kharkiv Region," the ministry said. 

Meanwhile, Moscow announced that its forces also destroyed a Ukrainian ammunition depot and artillery armament near Novooleksandrivka, Zaporozhye.