Hours earlier, two drones attacked a Russian city in a region next to the annexed Crimea Peninsula, officials said.

The Kremlin’s forces, meanwhile, attacked a medical clinic in Dnipro, in central Ukraine, killing a 69-year-old passer-by and another civilian. More than 20 others were wounded, including two children, Ukrainian officials said.

Also, a Russian S-300 missile hit a dam in the Karlivka district of Ukraine’s eastern Donetsk province, placing nearby settlements under threat of severe flooding.

Ukrainian President Volodymyr Zelenskyy condemned the blast in Dnipro as a war crime.

“Another Russian missile attack, another crime against humanity,” he wrote on Twitter. “The buildings of a psychological clinic and a veterinary clinic in the city of Dnipro were destroyed.”

Al Jazeera’s Natacha Butler, in Kyiv, reported other missile and drone strikes across Ukraine overnight.

“We certainly heard at least two very loud explosions at about four in the morning,” she said, adding that Ukraine’s armed forced claimed to have intercepted several missiles over the capital.

“We’ve been seeing intensified strikes on Ukraine,” she said. “Many say this is because Ukraine is looking very closely at Ukraine’s anticipated counteroffensive.”

The Belgorod town of Grayvoron, about seven kilometres (more than four miles) from the Ukrainian border, was under fire for several hours, with four houses, a store, a car, a gas pipeline and a power line damaged, Governor Vyacheslav Gladkov reported.

Closer to the border, a recreation centre, a shop and an uninhabited house sustained damage in the village of Glotovo. There were no casualties, according to Gladkov.

Earlier this week, the Belgorod region was the target of one of the most serious cross-border attacks from Ukraine since the war began 15 months ago.

Details of that raid, which began Monday and ended Tuesday, were murky. Russia blamed the Ukrainian armed forces, but two Russian groups said they were involved, with the aim of bringing down President Vladimir Putin.

Officials in Russia’s southern city of Krasnodar, in the region of the same name bordering Crimea, said that two drones hit there. Witnesses told local media they heard something like the sound of a moped and then two explosions.

“There is damage to buildings, but essential infrastructure was not damaged. And most importantly, there were no casualties,” Krasnodar governor Veniamin Kondratyev wrote on Telegram.

Krasnodar Mayor Yevgeny Naumov said there were no casualties.

Drone attacks against Russian regions on the border with Ukraine have been a regular occurrence since the start of the war, which began in February last year, with attacks stepping up last month.

Earlier this month, an oil refinery in Krasnodar was attacked by drones on two consecutive days

In another apparent incident of Kyiv’s forces harassing Russia, Ukraine’s defence ministry on Thursday published footage that appeared to show an unmanned drone boat attacking Russia’s Ivan Khurs reconnaissance ship in the Black Sea.

The video did not show the drone hitting the ship.

The video followed reports by Russia’s Ministry of Defence on Wednesday that Ukraine had launched an “unsuccessful” attack on the Ivan Khurs using three unmanned speedboats, with all three boats attacked and destroyed prior to reaching the ship.

Moscow released footage allegedly showing the destruction of one of the un-crewed boats.

Calls for armed Russian ‘self-defence’

After this week’s attack, the governors of Belgorod and Kursk said they favoured changing the law to allow local volunteer self-defence units to be armed when necessary.

“We have them [local self-defence units]. We have nearly 3,000 people in seven battalions along the border,” said Belgorod’s Gladkov.

Arming such forces could save the defence ministry from being forced to divert some of the troops it needs on the front line to respond to similar raids in future.

Roman Starovoit, governor of the Kursk region which also borders Ukraine, said he favoured the idea, too.

Last month, Andrei Turchak, first deputy speaker of the upper house of parliament, told President Vladimir Putin in a Kremlin meeting, “The legal status of these formations is now extremely restricted, and most importantly they do not have the right to carry and use weapons. We propose that this anomaly be eliminated at the legislative level.”

Colonel-General Andrei Kartapolov, an influential lawmaker who chairs the lower house of parliament’s defence committee, has also called for bigger structural changes to secure the border.