Ukraine Strikes Show Impact of New Weapons

The strike is the latest in a series that Ukraine has conducted against high-value targets such as ammunition depots and command posts since multiple-launch rocket systems known as Himars began arriving from the U.S. last month.

“The occupiers have already felt very well what modern artillery is, and they will not have a safe rear anywhere on our land,” Ukrainian President Volodymyr Zelensky said in a video address overnight.

Footage posted on social media by residents of Luhansk late Tuesday showed a large explosion. Russian military correspondents said on social media that an ammunition dump in Luhansk’s industrial area had been hit.

“The armed forces of Ukraine launched a massive attack on the military air-defense unit, which ensures the security of the city of Luhansk,” said Andriy Marochko, a spokesman for the self-proclaimed Luhansk People’s Republic people’s militia.

The Luhansk People’s Republic later said nine missiles had been fired at Luhansk from American-made Himars.

Russian forces claimed control over the whole of the Luhansk region earlier this month after weeks of grinding battle that has taken a heavy toll on both sides.

Serhiy Haidai, the exiled governor of Luhansk, said strikes on Russian ammunition depots had disrupted supplies, noting an increase in the activity of Russian subversion and reconnaissance groups probing Ukrainian lines for weak spots.

At the same time, Russia’s military has stepped up missile strikes on positions far from the front lines.

The death toll from a Russian strike on a residential building in Chasiv Yar over the weekend rose to 48, including a child, Mr. Zelensky said in his nightly address Wednesday. Nine people were pulled out of the rubble alive, he said.

Five civilians were killed in Russian artillery strikes on the southern region of Mykolaiv on Wednesday, said Kyrylo Tymoshenko, deputy head of the Ukrainian president’s office. He added that a hospital and residential buildings were damaged.

Russia also fired two missiles at the city of Zaporizhzhia in southeastern Ukraine, according to the regional military administration.

Russian troops shelled the Nikopol district of Dnipropetrovsk overnight using multiple-launch rocket systems, according to Ukrainian official Valentyn Reznichenko.

Since Russia took over Luhansk, it has targeted the Donetsk region, part of which is already controlled by Russia and separatist forces. Capturing the rest of the region would give Moscow full control of the Donbas area, which the Kremlin made its priority after pulling its forces out of central Ukraine in late March.

“In Donbas, offensive attempts do not stop, the situation there does not get easier, and the losses do not get smaller,” Mr. Zelensky said.

The Russia-backed head of the self-proclaimed Donetsk People’s Republic, Denis Pushilin, said Wednesday that Russian and separatist forces were progressing toward the towns of Siversk and Soledar, according to Russian state news agency TASS. The towns lie between Severodonetsk, which Russia captured late last month, and the city of Slovyansk, which is one of Moscow’s next targets, according to the Institute for the Study of War, a Washington-based think tank. Later Wednesday, a separatist official told TASS that the forces had entered the town limits of Soledar.

Mr. Pushilin also said that more than 100 cases of captured Ukrainian fighters are ready to be brought to court. Some of the cases would be heard by a court, others by tribunal, he said.

Last month, a court in the Donetsk People’s Republic sentenced three foreign fighters—two from the U.K., both of whom had lived for years in Ukraine before the conflict, and one from Morocco, who has Ukrainian nationality—to death, accusing them of working as mercenaries.

Mr. Pushilin said that the three men—Aiden Aslin and Shaun Pinner of the U.K. and Morocco-born Brahim Saadoun—had appealed their sentences but would face death by firing squad if their appeals are turned down.

Later Wednesday afternoon, TASS reported that North Korea had recognized the independence of the Donetsk and Luhansk People’s Republics, making it the third country to do so after Russia and Syria.

“The bilateral partnership will increase the geography of trade for our countries’ businesses,” Mr. Pushilin said, according to TASS.

After the announcement, Ukraine severed diplomatic ties with North Korea over the move.

“We view this decision as an attempt by Pyongyang to undermine the sovereignty and territorial integrity of Ukraine,” the Ukrainian Foreign Ministry said in a statement.

In Istanbul, officials from Ukraine, Russia, Turkey and the United Nations held talks on a proposal to export millions of tons of grain that have been trapped in Ukraine by Russia’s invasion.

The meeting among military officials from the three countries represented the first direct talks between Russia and Ukraine over a proposed corridor that would move grain on ships out through the Black Sea.

Also Wednesday, the European Commission issued new guidance on implementing sanctions to try to defuse tensions with Moscow over the blocking of some Russian goods from entering the Russian exclave of Kaliningrad, located between Poland and Lithuania along the Baltic Sea.

The guidance doesn’t eliminate sanctions for goods passing through EU territory from Russia to Kaliningrad, but seeks to smooth the passage of goods by allowing some sanctioned goods sent by rail to be waved through.

The Commission said that this exemption, which doesn’t include military or dual-use goods, should apply as long as transit volumes by rail remain within the historical average of the past three years. The EU countries bordering Kaliningrad—Poland and Lithuania—are supposed to ensure that is the case.

Some EU capitals, including Germany’s, were concerned that Lithuania’s enforcement of the sanction could trigger a dangerous escalation from the Kremlin, which has accused the Baltic country of imposing a blockade at Kaliningrad.

The new guidance won’t eliminate the need for Lithuania to carry out checks on goods but it could allow the two-way trade flows between Russia and Kaliningrad to face fewer hurdles.

Russian Foreign Ministry spokeswoman Maria Zakharova in a statement described the European Commission’s guidance as a “display of common sense.” But she added that Moscow still has questions about the document’s contents and would closely monitor their implementation.

—Laurence Norman contributed to this article.

Write to Isabel Coles at isabel.coles@wsj.com and Evan Gershkovich at evan.gershkovich@wsj.com