A third Russian airfield was ablaze on Tuesday from a drone strike, a day after Ukraine demonstrated an apparent new ability to penetrate hundreds of kilometers deep into Russian air space with attacks on two Russian air bases.
Officials in the Russian city of Kursk, located close to Ukraine, released pictures of black smoke above an airfield in the early morning hours of Tuesday after the latest strike. The governor said an oil storage tank there had been set ablaze but there were no casualties.
It came a day after Russia confirmed it had been hit hundreds of kilometers from Ukraine by what it said were Soviet-era drones - at Engels air base, home to Russia's strategic bomber fleet, and in Ryazan, a few hours' drive from Moscow.
Kyiv did not directly claim responsibility for the strikes but celebrated them.
"If Russia assesses the incidents were deliberate attacks, it will probably consider them as some of the most strategically significant failures of force protection since its invasion of Ukraine," Britain's ministry of defence said on Tuesday.
"The Russian chain of command will probably seek to identify and impose severe sanctions on Russian officers deemed responsible for allowing the incident."
Russia's defence ministry said three service members were killed in the attack at Ryazan. Although the attacks struck military targets it characterised them as terrorism and said the aim was to disable its long-range aircraft.
The New York Times, citing a senior Ukrainian official, said the drones involved in Monday's attacks were launched from Ukrainian territory, and at least one of the strikes was made with the help of special forces close to the base.
Ukraine never acknowledges responsibility for attacks inside Russia. Asked about the strikes, Ukrainian Defence Minister Oleskiy Reznikov repeated a longstanding joke blaming carelessness with cigarettes.
"Very often Russians smoke in places where it's forbidden to smoke," he said.
Ukrainian presidential adviser Oleksiy Arestovych went further, noting that Engels is Russia's only base fully equipped for the fleet of huge bombers Moscow has used to attack Ukraine.
"They will try to disperse (strategic aircraft) to airfields, but all this complicates the operation against Ukraine. Yesterday, thanks to their 'unsuccessful smoking', we achieved a very big result," he said.
Russian commentators on social media said that if Ukraine could strike that far inside Russia, it might also be able to hit Moscow.
The huge Tupolev long-range bombers that Russia stations at Engels are a major part of its strategic nuclear arsenal, similar to the B-52s deployed by the United States during the Cold War. Russia has used them in its campaign since October to destroy Ukraine's energy grid with near weekly waves of missile strikes.
The Engels base, near the city of Saratov, is at least 600 km (372 miles) from the nearest Ukrainian territory.
Russia responded to Monday's attacks with what it called a "massive strike on Ukraine's military control system", though it did not identify any specific military targets for what Ukraine called Moscow's latest strikes on civilian infrastructure.
Missiles across Ukraine destroyed homes and knocked out power, but the impact seemed to be less severe than barrages last month that plunged millions of Ukrainians into darkness and cold.
Ukraine's air force said it had shot down more than 60 of around 70 missiles. President Volodymyr Zelenskiy said at least four people were killed.
A missile tore a huge crater out of the earth in the village of Novosofiivka, about 25 km (16 miles) east of Zaporizhzhia city in southern Ukraine, and completely shredded a nearby house. Ambulance workers collected two bodies lying by a destroyed car.
Olha Troshyna, 62, said the dead were her neighbours who were standing by the car seeing off their son and daughter-in-law when the missile struck. With houses now destroyed and winter setting in, she had no idea where she would go.
"We have no place to go back to," she said. "It would be fine if it were spring or summer. We could have done something if it were a warm season. But what am I going to do now?"
On Tuesday, Zelenskiy visited troops in the Donbas region in the east of the country that has seen the war's heaviest fighting.
He praised soldiers in a selfie video filmed in front of a sign on the road outside Sloviansk, near the city of Bakhmut that Russian forces have been trying to encircle for weeks in one of the war's bloodiest campaigns. In other videos, he presented medals and shook hands with troops in a hangar.
Kyrylo Budanov, head of Ukraine's Defence Intelligence agency, said Moscow had enough missiles left for just a few more giant barrages before they were depleted.
Russia claims a military justification for attacks on Ukraine's civil infrastructure. Kyiv says the strikes are intended to hurt civilians, a war crime.
"They do not understand one thing - such missile strikes only increase our resistance," Ukraine's defence minister Reznikov said.
No political talks are underway to end the war. Moscow insists it will not negotiate unless Kyiv and the West accept its sovereignty over Ukrainian lands it claims, while Kyiv says Russia must quit all its territory.
Kremlin spokesman Dmitry Peskov said on Tuesday talks would only be possible when Russia achieves the goals of its "special military operation", which he did not define.
"Russia must and will achieve the goals it has set," he said "As for the prospects for some kind of negotiations, we don't see them at the moment, we have repeatedly said so."
However, the sides have discussed issues such as prisoner swaps. A Russian-installed official said the latest such exchange would see each side free 60 prisoners later on Tuesday.