Russian President Vladimir Putin said Monday that Moscow would step up its strikes on military targets in Ukraine, two days after Kyiv's deadly attack on the Russian city of Belgorod.

"We're going to intensify the strikes. No crime against civilians will rest unpunished, that's for certain," he said during a visit to a military hospital, referring to the 24 dead and 100 wounded in Saturday's assault.

Putin accused Ukrainian forces of targeting "right in the city center, where people were walking around, before New Year's Eve."

He said Moscow's forces would continue to hit what he called Ukrainian "military installations," upping the ante following more than 22 months of conflict.

Ukraine's strike on Belgorod came as apparent retaliation for Russia's worst aerial bombardment of Ukrainian cities since the battle for Kyiv in the early weeks of the war, which also targeted the capital Kyiv last week. The Russian attack killed 39 people.

In his New Year's address, Ukrainian President Volodymyr Zelenskyy vowed to hit Russia with the "wrath" of Ukraine's bolstered military capabilities.

Concurrent New Year's Day attacks by Moscow and Kyiv

The two militaries launched new attacks on Sunday and early Monday. According to a Russian-installed official in the eastern region of Ukraine, shelling authorized by Kyiv killed four people.

Denis Pushilin, the Russian-appointed head of the Donetsk region, wrote on Telegram that "heavy shelling" by Ukrainian forces also left 14 people injured.

Meanwhile, Ukrainian officials said Russian air attacks on Odesa in the south killed at least one person.

Oleh Kiper, governor of the Odesa region, said on Telegram that several people were injured by falling debris after a Russian drone attack caused fires in some residential buildings. Kiper added that Ukraine's air defense systems were engaged in repelling the drones.

Ukraine's air force said Russia's air attacks also targeted the Mykolaiv and Dnieper regions, while governor Maksym Kozytskyi of Lviv said air defense systems were engaged in repelling a Russian drone attack on the city in the west.

Zelenskyy warns of Ukrainian "wrath"

As the violence surged between Ukraine and Russia, Zelenskyy said Ukraine was ramping up military industry in 2024.

In his televised New Year's address, the Ukrainian president said, "Next year, the enemy will feel the wrath of domestic production."

Zelenskyy announced at least "a million" additional drones as well as F-16 fighter jets promised by its Western partners.

"No matter how many rockets the enemy launches, no matter how many shellings and attacks — vile, merciless, massive — the enemy carries out in an attempt to break Ukrainians, intimidate, knock Ukraine down, drive it underground, we will still rise," he said.

mm, ss/sms (Reuters, AFP)