Russia's Black Sea fleet's flagship has sunk following what Kyiv claims was a Ukrainian missile strike, striking one of the most severe blows yet to Moscow's war effort and serving as a shocking image of Kyiv's defiance to a better-armed adversary.

Kyiv claims it fired missiles from the coast at the warship Moskva. Russia did not confirm the attack but stated that the ship sank while being pulled through rough seas following a fire caused by an ammo explosion.

Moscow reported that about 500 sailors were evacuated. There has been no independent confirmation of the crew's fate.

Although Russia denied that Ukrainian missiles struck the ship, it hit an alleged retaliatory plant in Kyiv that manufactured and refurbished anti-ship missiles early on Friday.

The Moskva was by far Russia's largest vessel in the Black Sea fleet, armed with guided missiles capable of attacking the shore and shooting down planes and radar capable of providing air defense cover for the fleet.

On the first day of the conflict, Feb. 24, the ship ordered Ukrainian defenders of an island outpost to surrender. They radioed back an obscenity; an event commemorated on a postage stamp printed by Kyiv hours before declaring victory.

President Volodymyr Zelenskyy repeated a portion of that term in an overnight address, paying tribute to "those who demonstrated that Russian ships can go — only to the bottom."

Russia has imposed a naval blockade on Ukrainian ports and threatened an amphibious landing along the coast. Without a flagship, Russia's ability to threaten Ukraine from the sea may be severely limited.

"If the sinking of the Moskva is confirmed, it will be emblematic of Russia's overall military effort thus far," tweeted Michael Kofman, a military expert who described it as a "significant loss for the Russian navy."

Since the British torpedoed Argentina's General Belgrano during the 1982 Falklands war, no warship of this size has been sunk in combat.

Kyiv explosions

On Friday, Kyiv was struck by some of the most intense explosions heard in the area since Russian soldiers retreated two weeks ago. Moscow claimed responsibility for attacking a capital plant that manufactured and refurbished Ukrainian weaponry, including anti-ship missiles.

"The number and magnitude of missile strikes against Kyiv targets will increase in response to any terrorist attacks or acts of sabotage on Russian territory committed by the Kyiv nationalist regime," the Russian Defense Ministry stated.

Kirill Kyrylo, 38, a worker at a car repair shop, said he witnessed three explosions hit an industrial building across the street, igniting a fire that firefighters eventually extinguished.

"The building was on fire, and I was forced to take cover behind my car," he explained, pointing off the shattered glass of the repair shop and shards of metal that had flown across from the burning building across the street.

Russia's defense ministry also announced the capture of Mariupol's Ilyich steel plant, one of the last industrial sites to hold out in the besieged eastern city that has endured the war's most intense fighting and greatest humanitarian crisis.

Ukraine claimed victory over Russian offensives in the towns of Popasna and Rubizhne, north of Mariupol. Both reports were unable to be independently verified.

Russia withdrew its soldiers from northern Ukraine earlier this month after a massive armored attack on Kyiv was repulsed on the capital's outskirts.

Moscow has openly said that its primary objective in the war is to seize the Donbas, an eastern region of two provinces that is already partially held by Russian-backed rebels and to which Moscow wants Kyiv to submit. It has moved a new column of thousands of troops into the east in preparation for a big attack, which Ukraine anticipates.

Moscow has stated that it hopes to seize all of Mariupol soon, which would make it the country's only major metropolis.

Seven weeks of siege and bombing have turned the Black Seaport, which was home to 400,000 people before the war, to rubble, with tens of thousands of civilians trapped inside. There have been thousands of civilian deaths.

Russia first stated that its objectives in Ukraine were to disarm its neighbor and combat nationalists.

Kyiv and its Western supporters contend that these are fabricated grounds for an unjustified war of aggression that has displaced a fifth of Ukraine's 44 million people.