Kyiv faced on Monday a barrage of "kamikaze" drone strikes that hit key infrastructure in and around the Ukrainian capital.
The strikes came right before Russian President Vladimir Putin heads for Belarus, fuelling fears he will pressure his ex-Soviet ally to join a new offensive on Ukraine.
The Ukrainian Air Force said its air defenses shot down 30 drones, the third Russian air attack on the Ukrainian capital in six days and the latest in a series of assaults since October that have targeted the Ukrainian power grid, causing sweeping blackouts amid sub-freezing temperatures.
Kyiv's mayor said no one had died or been wounded in the attacks on Kyiv that rocked the capital's Solomianskyi and Shevchenkivskyi districts, according to preliminary information.
"Kamikaze" drones are cheaply produced, disposable unmanned aircraft that fly towards their target before plummeting at velocity and detonating on impact.
Under the darkness of night, a fire raged at one site at an energy facility in the often targeted central Shevchenkivskyi district, a Reuters witness said.
"I heard an explosion. And in three or four minutes I heard another explosion," said an old man who works at a guard at a nearby hospital.
The Solomianskyi district in the western part of Kyiv is a busy transport hub, home to a train station and one of the city's two passenger airports.
Kyiv officials said 18 out of 23 drones were shot down over the city of 3.6 million.
"As a result of the attack on the capital, critical infrastructure facilities were damaged," Vitali Klitschko said on the Telegram messaging app.
"Energy and heating engineers are working to quickly stabilize the situation with energy and heat supply."
Olesky Kuleba, governor of the region surrounding Kyiv, said infrastructure and private houses were damaged and that two people were wounded. He said the attack caused "fairly serious" damage and three areas in the region had been left without power.
Ukraine's national power grid operator, Ukrenergo, said on Telegram drones targeted power plants across the country.
"Currently, the most difficult situation is in the central, eastern and Dnipro regions," it said.
There has been constant Russian and Belarusian military activity for months in Belarus, a close Kremlin ally that Moscow's troops used as a launch pad for their abortive attack on Kyiv in February.
Putin's visit, for talks with Belarusian leader Alexander Lukashenko, will be his first to Minsk since 2019 – before the pandemic and a wave of Belarusian protests in 2020 that Lukashenko crushed with strong support from the Kremlin.
Lukashenko has said repeatedly he has no intention of sending his country's troops into Ukraine.
"During (these talks) questions will be worked out for further aggression against Ukraine and the broader involvement of the Belarusian armed forces in the operation against Ukraine, in particular, in our opinion, also on the ground," Ukrainian joint forces commander Serhiy Nayev said.
Russian troops that moved to Belarus in October will conduct battalion tactical exercises, the Russian Interfax news agency reported, citing the Russian defense ministry.
It was not immediately clear when they would start.
The 10-month-old conflict in Ukraine is the biggest in Europe since World War II, killing tens of thousands of people, driving millions from their homes and reducing cities to ruins.
Ukrainian President Volodymyr Zelenskyy said the armed forces were holding firm in the town of Bakhmut – the scene of the fiercest fighting for many weeks as Russia attempts to advance in eastern Ukraine's Donetsk region.
"The battlefield in Bakhmut is critical," he said. "We control the town even though the occupiers are doing everything so that no undamaged wall will remain standing."
Zelensky on Monday called on Western leaders meeting in Latvia, including British Prime Minister Rishi Sunak, to supply a wide range of weapons systems.
Denis Pushilin, the Russian-installed administrator of the portion of the Donetsk region controlled by Moscow, said that Ukrainian forces shelled a hospital in Donetsk city, killing one person and injuring several others.
Russia's defense ministry said over the past 24 hours its forces had shot down four U.S.-made HARM anti-radiation missiles over the Belgorod region, which borders Ukraine, the state-run TASS news agency reported.
Reuters could not independently verify the battlefield accounts.
Putin casts what he calls Russia's "special military operation" in Ukraine as the moment when Moscow finally stood up to the Western bloc, led by the United States, seeking to capitalize on the 1991 fall of the Soviet Union by destroying Russia.
Kyiv and the West say that assertion is absurd and that Putin has no justification for what they see as an imperial-style war of aggression that has resulted in Russia now controlling around a fifth of Ukraine.
Moscow said on Monday Russian and Chinese forces would hold joint naval drills between Dec. 21 and Dec. 27, involving missile and artillery firing in the East China Sea.
While the drills have been held annually since 2012, Moscow has sought to strengthen its political, security and economic links with Beijing in recent months and sees Chinese President Xi Jinping as a key ally in an anti-West alliance.