Ukraine's capital Kyiv has been rocked by explosions as Russia launched a rare overnight attack on the city.
No-one was killed and most of the missiles were shot down, Ukrainian officials said, but some did hit "critical infrastructure", causing a blackout across the region.
The attack occurred before Russia's President Vladimir Putin arrived in Belarus to meet Alexander Lukashenko.
Ukraine has warned that Russia may be preparing a new attack from Belarus.
This latest barrage of missile attacks from Russia is the third in five days – however night time raids on the capital, Kyiv, are unusual.
Twenty-three Iranian missiles were launched, of which 18 were shot down, the head of Kyiv's military administration, Serhiy Popko said.
Pictures online show firefighters at a large blaze at a power plant.
Only two people were injured, authorities reported – a very low number considering many people would have been asleep at the time of the strikes on civilian areas.
Kyiv's Mayor Vitaliy Klitschko wrote on Telegram that "critical infrastructure facilities were damaged" and that engineers were working to restore power.
Temperatures in Kyiv regularly drop below freezing and are set to fall further in January.
Last Friday, Russia launched a barrage of missiles in one of the largest air strikes on the capital since the start of the war, and Kyiv has accused Moscow of using winter as a weapon, by attacking civilian infrastructure like its energy grids.
At the weekend, Ukraine's President Volodymyr Zelensky warned that Russia could be planning another major ground offensive early next year, using Belarus as a launching pad for the attack.
However, several experts have said they have seen no evidence so far of preparations for a new push, and question whether Moscow would be able to do it over the winter.
Belarus shares a border with both Russia and Ukraine, and Alexander Lukashenko is a close ally of President Putin.
On Monday, the Russian leader was greeted by his Belarusian counterpart at Minsk National Airport.
While Belarus has not become involved in the war directly, it did allow Russian troops to use its territory to launch the invasion in February.
Minsk is coming under increasing pressure from Moscow to step up its support in the so-called "special military operation".
But Mr Putin's spokesperson described suggestions that Russia was pressuring Belarus to join the war as "stupid and unfounded fabrications".
Mr Putin arrived in Minsk to meet the Belarusian leader shortly after Russia's defence ministry announced that its troops stationed in Belarus will conduct joint military exercises – which will further fuel Kyiv's concerns of a fresh incursion.
In his nightly address on Sunday, President Zelensky said that protecting Ukraine's borders is a constant priority, and he was preparing defences for all scenarios.
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