Recent explosions at air force bases deep inside Russia have apparently caused serious concerns in the country. Russia's defense ministry has claimed that Ukraine attempted to attack military aircraft using drones.

President Vladimir Putin on Tuesday convened a security council meeting following the explosions at airfields in the central and southern regions of the country on the previous day.

A Russian presidential spokesperson indicated that officials immediately discussed their response to the attacks.

The governor of the western region of Kursk, which borders Ukraine, also said on social media that an oil storage tank near an airfield was hit by a drone attack on Tuesday.

Ukraine's government has not issued an official statement on the matters.

But the Washington Post reported on Tuesday a senior Ukrainian official admitted that all three attacks were carried out by Ukrainian drones. The newspaper said the official noted that strikes were "very successful, very effective."

Multiple Russian media outlets said the drones were the improved version of spy drones made in the Soviet era.

Russian newspaper Izvestia on Wednesday carried a view that the airbases are supposed to be equipped with stable air defense systems, but they were apparently not fully prepared to strike back at new Ukrainian weapons.

Independent Russian online media outlet Meduza also reported on Wednesday that the attack on the airbase more than 600 kilometers from the border with Ukraine was a huge turning point. It added that Russian troops are forced to build air defense systems deep inside the country as well as on the Ukrainian frontline and border.