At least 10 people were killed in the missile strikes.
Russian President Vladimir Putin says the missile strikes on Kyiv and other Ukrainian cities on Monday were Moscow's response to Saturday's attack on the Kerch Bridge, which connects Russia and Crimea.
The bridge -- the rail section of which Vladimir Putin inaugurated in 2019 -- was hit by what Moscow said was a truck bomb.
The blast knocked part of the bridge into the sea, while fire spread to a train on the railway section, above.
The bridge holds important strategic and symbolic value to Russia, which annexed Crimea from Ukraine in 2014.
"The Kyiv regime, by its actions, has actually put itself on the same level as international terrorist formations, with the most odious groups," said Putin.
"To leave crimes of this kind unanswered is simply impossible. This morning, at the suggestion of the Ministry of Defense and according to the General Staff of Russia's plan, a massive strike was carried out with precision weapons: long-range air, sea and land-based facilities at energy, military command and communications in Ukraine.
"If terrorist attacks continue on our territory, responses from Russia will be harsh," said Putin.
Ukraine president Volodymyr Zelenskyy said Russian forces launched dozens of missiles and Iranian-built drones against Ukraine.
The targets were civilian areas and energy facilities in 10 cities, Zelenskyy said in a video address.
“(The Russians) chose such a time and such targets on purpose to inflict the most damage,” he said.