Russia also hit military bases in central and eastern Ukraine, according to the Ministry of Defence, quoted in Russian media.
It claimed to have targeted Ukrainian defence and energy infrastructure in response to recent attacks on Russian power stations from Moscow to the Black Sea.
The attacks led to a rare concession by Russian President Vladimir Putin that his country was facing fuel shortages.
On Wednesday, Zelensky cut short his visit to Dublin after he said fresh intelligence had emerged suggesting that Moscow was planning to strike Ukraine.
“I urge our people to be especially careful, to protect themselves, their children, and, of course, their families,” he said.
He added that Russian President Vladimir Putin “has been preparing this massive strike against Ukraine for some time now”.
Poland has also activated fighter jets to protect its airspace, describing it as a “preventative” measure. There are no reports of attacks on Polish territory.
“These actions are of a preventive nature and are aimed at securing and protecting the airspace, especially in areas adjacent to the threatened regions,” Poland’s military wrote on X., external
Poland is a member of Nato, a signatory to the military alliance’s Article 5 provision that states “an armed attack against one Nato member shall be considered an attack against them all”.
Russian troops recently advanced into the city of Kostyantynivka, one of Ukraine’s last key bulwarks in the east. If Moscow secures the city, it would provide a gateway to the entire Donbas region.
Meanwhile, Ukrainian commanders say they have recaptured more territory this year than they have lost, disrupting Moscow’s crucial supply lines between the Russian border and occupied Crimea.
The war has otherwise stalled for months with each side’s troops largely entrenched in their positions.
Russia controls approximately one-fifth of Ukrainian territory, mostly seized in the first few months of its full-scale invasion in February, 2022.
