Ukraine’s president said Russia is trying to starve his country’s cities into submission but warned Saturday that continuing the invasion would exact a toll on Russia for “generations.” The remarks came after Moscow held a mass rally in support of its bogged-down forces.

Ukrainian President Volodymyr Zelenskyy accused the Kremlin in an overnight video address of deliberately creating “a humanitarian catastrophe ” and appealed again for Russian President Vladimir Putin to meet with him to prevent more bloodshed.

Noting that the 200,000 people reported to have attended the rally was similar to the number of Russian forces deployed to Ukraine, Zelenskyy said Friday’s event in Moscow illustrated the stakes of the largest ground conflict in Europe since World War II.

“Picture for yourself that in that stadium in Moscow there are 14,000 dead bodies and tens of thousands more injured and maimed,” the Ukrainian leader said, standing outside the presidential office in the capital, Kyiv. “Those are the Russian costs throughout the invasion.”

Putin lavished praised on his country’s military forces during Friday’s flag-waving rally, which took place on the anniversary of Russia’s 2014 annexation of Crimea from Ukraine. The event included patriotic songs such as “Made in the U.S.S.R.,” with the opening lines “Ukraine and Crimea, Belarus and Moldova, it’s all my country.”

“We have not had unity like this for a long time,” Putin told the cheering crowd.

Taking to the stage where a sign read “For a world without Nazism,” he railed against his foes in Ukraine with a baseless claim that they are “neo-Nazis” and insisted his actions were necessary to prevent “genocide” — an idea flatly rejected by leaders around the globe.

The rally took place as Russia has faced heavier-than-expected losses on the battlefield and increasingly authoritarian rule at home. Russian police have detained thousands of antiwar protesters.

Fighting raged on multiple fronts in Ukraine more than three weeks after Russia’s Feb. 24 invasion.

The northwest Kyiv suburbs of Bucha, Hostomel, Irpin and Moshchun were under fire on Saturday, the Kyiv regional administration reported. The city of Slavutich, located 165 kilometers (103 miles) north of the capital was “completely isolated,” the administration said.

In the besieged port city of Mariupol, the site of some of the war’s greatest suffering, Ukrainian and Russian forces battled over the Azovstal steel plant, one of the biggest in Europe, Vadym Denysenko, adviser to Ukraine’s interior minister, said Saturday.

“One of the largest metallurgical plants in Europe is actually being destroyed,” Denysenko said in televised remarks.

The Russian military reported Saturday that it has used its latest hypersonic missile for the first time in combat. A spokesman for the Russian Defense Ministry, Maj. Gen. Igor Konashenkov, said Kinzhal missiles destroyed an underground warehouse storing Ukrainian missiles and aviation ammunition in the western Ivano-Frankivsk region of Ukraine.

Russia has said the Kinzhal, carried by MiG-31 fighter jets, has a range of up to 2,000 kilometers (about 1,250 miles) and flies at 10 times the speed of sound.

A Ukrainian military official confirmed a Friday missile strike on a military warehouse in the Delyatyn settlement of the Ivano-Frankivsk region, but he told the Ukrainskaya Pravda newspaper Saturday that authorities have not yet verified the type of missile used.

Konashenkov said Russian forces also used the anti-ship Bastion missile system to strike Ukrainian military facilities near the Black Sea port of Odesa. Russia first used the weapon during its military campaign in Syria in 2016.

Ukrainian and Russian officials agreed to establish 10 humanitarian corridors for bringing aid in and residents out — one from Mariupol and several around Kyiv and in the eastern Luhansk region, Ukrainian Deputy Prime Minister Iryna Vereshchuk said Saturday.

She also announced plans to deliver humanitarian aid to the southern city of Kherson, which was seized by Russian forces.

In a separate development, Norway said four U.S. service members died in a plane crash during NATO drills in that country’s north. The annual exercise, “Cold Response,” is unrelated to the war in Ukraine.

In his nightly video address, Zelenskyy said Russian forces were blockading the largest cities with the goal of creating such miserable conditions that Ukrainians will surrender. But he warned that Russia would pay the ultimate price.

“The time has come to restore territorial integrity and justice for Ukraine. Otherwise, Russia’s costs will be so high that you will not be able to rise again for several generations,” he said.

In the wake of the invasion, the Kremlin has clamped down harder on dissent and the flow of information, banning sites such as Facebook and Twitter, and instituting tough prison sentences for what is deemed to be false reporting on the war, which Moscow refers to as a “special military operation.”

Vladimir Medinsky, who has led Russian negotiators in several rounds of talks with Ukraine, said Friday that the two sides have moved closer to agreement on the issue of Ukraine dropping its bid to join NATO and adopting a neutral status. In remarks carried by Russian media, he said the sides are now “halfway” on issues regarding the demilitarization of Ukraine.

However, Mikhailo Podolyak, an adviser to Zelenskyy, alleged that Moscow’s characterization was intended “to provoke tension in the media.” He tweeted: “Our positions are unchanged. Ceasefire, withdrawal of troops & strong security guarantees with concrete formulas.”

Britain’s foreign minister accused Putin of using the talks as a “smokescreen” while his forces regroup. “We don’t see any serious withdrawal of Russian troops or any serious proposals on the table,” Foreign Secretary Liz Truss told the Times of London newspaper.

The British Department of Defense said in its latest intelligence assessment that the Kremlin “has been surprised by the scale and ferocity of Ukrainian resistance” and “is now pursuing a strategy of attrition” that is likely to involve indiscriminate attacks.

U.S. Defense Secretary Lloyd Austin, during a Saturday visit to NATO ally Bulgaria, said the Russian invasion had “stalled on a number of fronts” but the U.S. had not yet seen signs that Putin was deploying additional forces.

Around Ukraine, hospitals, schools and buildings where people sought safety have been attacked. Ludmyla Denisova, the Ukrainian Parliament’s human rights commissioner, reported Friday that at least 130 people survived the Wednesday bombing of a Mariupol theater that was being used a shelter, but another 1,300 were believed to be still inside.

“We pray that they will all be alive, but so far there is no information about them,” Denisova told Ukrainian television.

Satellite images on Friday from Maxar Technologies showed a long line of cars leaving Mariupol as people tried to evacuate. Zelenskyy said more than 9,000 people were able to leave the city in the past day along a route that leads 227 kilometers (141 miles) northwest to the city of Zaporizhzhia.

The governor of the Zaporizhzhia region, Oleksandr Starukh, announced a 38-hour curfew in the southeastern city after two missile strikes on its suburbs killed nine people Friday.

The Russian forces fired at eight cities and villages in the eastern Donetsk region in the past 24 hours: Mariupol, Avdiivka, Kramatorsk, Pokrovsk, Novoselydivka, Verkhnotoretske, Krymka, and Stepne, Ukraine’s National Police said in a statement Saturday.

The attacks with rockets and heavy artillery killed and injured dozens of civilians, and damaged at least 37 residential buildings and infrastructure facilities, the statement posted on Telegram said.

“Among the civilian objects that Russia destroyed are multistory and private houses, a school, a kindergarten, a museum, a shopping center and administrative buildings,” the statement said.