Ukraine's military raised air alerts nationwide on Tuesday, warning there was a threat of missile strikes from Russian bombers.
"Missile danger in areas where the air alert is on! Threat of launching cruise missiles from Tu-95MS aircraft. A total of 16 Tu-95MS strategic bombers are in the air," the air force said on Telegram.
Hours earlier, the military warned that about 20 Russian strategic bombers were airborne.
After takeoffs detected from the far northern Olenya airfield and southern Engels airbase, there were multiple Tupolev Tu-95MS bombers in Russia's airspace, military officials said on Telegram.
Another four Tu-22M3 bombers had departed from Russia's Shaikovka airfield near the Belarus border.
The air force had also reported the takeoff of Tu-95s, which date back to the Soviet era, on December 29.
On that day, Russia launched a wave of strikes across Ukrainian cities, including the capital, which killed 39 people.
About two hours after midnight Tuesday, explosions rang out in Kyiv as Ukraine's air force battled a drone attack on the capital, officials said.
Kyiv mayor Vitali Klitschko reported explosions and a fire in the capital about an hour after the region's military administration said unmanned aerial vehicles (UAVs) or drones had been detected in the city's airspace.
Mykolayiv's mayor said the air force had downed drones in the city, with debris causing a fire.
The air force said it had downed 35 Iranian-made Shahed drones launched by Russia overnight.
Tuesday's attacks come a day after Russian President Vladimir Putin said that his forces would intensify strikes on military targets in Ukraine, after an unprecedented Ukrainian attack over the weekend on the Russian city of Belgorod. That attack, on Saturday, killed 25 people including five children.
Moscow also hit Ukrainian cities on New Year's Eve, with Kyiv saying it had foiled a "record" number of drones launched by Russia.