A Russian missile strike killed at least three people in a residential building in the southern Ukrainian city of Mykolaiv on Wednesday while the search continues for dozens still missing after the attack on a shopping mall in Kremenchuk in central Ukraine two days ago.

In the east, the governor of Luhansk province said there was "fighting everywhere" in the battle around the city of Lysychansk, which Russian troops were trying to encircle.

The governor of Kryvyi Rih in central Ukraine said Russian shelling had increased there too in the past few days.

"Several villages have been wiped from the face of the earth," Oleksander Vilkul said.

The stepped-up attacks took place as Russian President Vladimir Putin's forces make slow but inexorable progress in a conflict now in its fifth month.

Nonetheless, Western analysts say the Russians are taking heavy casualties and running through resources, while the prospect of more Western weapons supplies reaching Ukraine, including long-range missile systems, made Moscow's need to consolidate any gains more urgent.

On the diplomatic front, leaders of NATO countries were meeting in the Spanish capital Madrid to thrash out policy in response to what Russia calls its "special military operation."

NATO leaders are set to label Russia a menace to their security as they overhaul the alliance's defenses in response to the ongoing war in Ukraine, Secretary-General Jens Stoltenberg said on the second day of a NATO summit. "We'll state clearly that Russia poses a direct threat to our security," he said.

The military alliance faces its biggest challenge since World War II amid the war in Ukraine, he added.

Stoltenberg also said NATO allies meet "in the middle of the most serious security crisis we have faced," as he arrived at the alliance's summit in Madrid. "This will be a historic and transformative summit."

German Chancellor Olaf Scholz, for his part, said members of the military alliance would continue to supply Ukraine with weapons for as long as necessary.

Meanwhile, Russia's Supreme Court on Wednesday postponed for the second time a hearing on whether to designate Ukraine's Azov Regiment, which defied besieging Russian forces for weeks in Mariupol, as a terrorist entity.

A court official said the hearing, first set for May 26, had now been rescheduled for Aug. 2. However, no reason was given.

Civilian casualties

The mayor of Mykolaiv, Oleksandr Senkevych, said eight Russian missiles had struck the city, including hitting an apartment block. Photographs showed smoke billowing from a four-story building with its upper floor partly destroyed.

A river port and ship-building center just off the Black Sea, Mykolaiv has been a bastion against Russian efforts to push West toward Ukraine's main port city of Odessa.

The Kremenchuk attack drew international condemnation. Moscow denied targeting the mall and said it had struck an arms depot nearby, which exploded.

Ukrainian President Volodymyr Zelenskyy's office said the Russians had also fired missiles at civilian infrastructure in the Sumy region in the past 24 hours, killing two civilians.

Britain's Defense Ministry, in its regular assessment of the conflict, said it expected Russia to continue making strikes in an effort to hamper the resupplying of Ukrainian forces on the frontlines.

"Russia's shortage of more modern precision strike weapons and the professional shortcomings of their targeting planners will highly likely result in further civilian casualties," it said.

Ukrainian armed forces commander Gen. Valery Zaluzhny said Russia had fired around 130 missiles on Ukraine in the last four days – an indication of the intensification of attacks.

Russia has denied targeting civilian areas but the United Nations says at least 4,700 civilians have been killed since Russia invaded Ukraine on Feb. 24.

Zelenskyy addressed the U.N. Security Council remotely on Tuesday, describing Russia as a "terrorist state" and urging the Security Council, where Moscow has a veto, to expel Russia from the United Nations.

Eastern front

Fighting meanwhile raged further east in Luhansk province, a key battleground in Russia's assault on the industrial heartland of the Donbass region.

"There is fighting everywhere. The enemy is trying to break through our defenses. And since they don't succeed, they fire with all the weapons they have, erase all the villages from the face of the earth," Luhansk governor Serhiy Gaidai said on television.

The battle for Lysychansk follows the fall of Severodonetsk, its sister city across the Severskyi Donets River on Saturday.

Its capture would expand Russian control of the Donbass, one of Moscow's strategic objectives since its failure to seize Ukraine's capital Kyiv in the early stages of the war.

"The Russians are using every weapon available to them ... and without distinguishing whether targets are military or not - schools, kindergartens, cultural institutions," Gaidai said.

Referendum

The Moscow-imposed military-civilian administration in the Kherson region said it had begun preparations for a referendum on joining Russia, Russian state news agency TASS reported.

Kherson, a port city on the Black Sea, sits just northwest of the Russian-annexed Crimean peninsula.

Pro-Russian authorities said Wednesday they were launching bus and train services between Moscow-annexed Crimea and the southern Ukrainian regions of Kherson and Zaporizhzhia.

"Starting from July 1, regular bus and train services between Crimea and the regions of Kherson and Zaporizhzhia will be launched for the first time in eight years," Sergei Aksyonov, the pro-Moscow head of Crimea, said on messaging app Telegram.

Members of Russia's National Guard will ensure the safety of travel, he added.

Russia-installed officials said their security forces had detained Kherson city mayor Ihor Kolykhayev on Tuesday after he refused to follow Moscow's orders. A local official said the mayor was abducted.

In the past few days, Ukrainians have also described attacks in the Odessa region and Kharkiv in the northeast.