A new blast hit an airbase inside Russia on Tuesday, the latest in a series of apparent Ukrainian drone attacks that showcase an ability to strike at the heart of Russian territory and could mark a new boldness in Kyiv's fightback against Moscow's war.
An airfield at Kursk in southwest Russia was ablaze on Tuesday morning, with regional governor Roman Starovoit saying the incident was the result of a drone attack.
Photos and video verified by NBC News showed a large fire at the airfield caused by a suspected damaged oil tanker, with smoke trailing miles across the sky of the area, which borders Ukraine.
Similar explosions were seen on Monday at the Engels air base outside the city of Saratov and at Ryazan, just 125 miles southwest of Moscow and hundreds of miles away from the Ukrainian border.
The Engels base houses Russia's strategic bombing fleet of tu-160 and tu-95 planes, which have been used on long-range bombing missions to Ukraine and can be adapted to carry nuclear weapons.
Ukraine has not directly claimed responsibility, but officials have jokingly suggested its military may be behind the incidents. Russia’s defense ministry blamed Kyiv’s forces for the two blasts Monday, in which it said three “maintenance personnel” died and two planes were damaged.
Analysts were cautious about the military impact of the apparent attacks on strategic sites far from the front lines, but said they had further undermined Russian confidence in the country's air defenses while providing a timely morale boost for Ukrainian civilians enduring a long winter under bombardment.
“The signaling is important for the Ukrainians: they need to know that they are hitting back, given the amount of pain and devastation and general discomfort that’s being meted out in Ukraine," Matthew Ford, an associate professor at the Swedish Defense University in Stockholm, told NBC News.
"It’s important from a morale point of view that some Russian strategic resources are being targeted."
Russia has the firepower to carry on bombing Ukraine, he added. "It might be a pain but they can relocate aircraft and infrastructure, they can put up more security around air bases."
The attacks were inflicted, the Kremlin said, by "Soviet-made UAV," or unmanned aerial vehicles. This suggests Ukraine is not using the billions of dollars' worth of lethal aid it has received from the United States and other Western allies in attacks on Russian soil, which Washington has feared could trigger an escalation.
