In one of the starkest signs yet that despite the weeks of hell Vladimir Putin has unleashed on Ukraine his plans to conquer it are sinking, the flagship of Russia’s Black Sea fleet is now at the bottom of the Black Sea. 

It has now been confirmed that the guided-missile cruiser Moskva, which became a potent target of Ukrainian defiance in the opening days of the war, sank Thursday.

The British Ministry Defense said via Twitter Friday morning that Russia has admitted that the Soviet-era, Slava-class cruiser has sunk. It added that the Moskva served a key role as both a command vessel and air defense node.

Ukrainian officials said their forces hit the vessel with missiles, while Russia acknowledged a fire aboard the Moskva but no attack. U.S. and other Western officials could not confirm what caused the blaze.

The loss of the warship named for the Russian capital is a devastating symbolic defeat for Moscow as its troops regroup for a renewed offensive in eastern Ukraine after retreating from much of the north, including around the capital, Kyiv.

In his nightly video address to the nation, President Zelensky alluded to the sinking as he told Ukrainians they should be proud of having survived 50 days under attack after the Russians “gave us a maximum of five.”

Listing the many ways Ukraine has defended against the invasion, he noted those “who showed that Russian warships can sail away, even if it’s to the bottom” of the sea. It was his only reference to the missile cruiser.

Powerful explosions were heard in Kyiv and other Ukrainian cities only hours after reports emerged that the Russian warship attacked by Ukraine had sunk, Sky News reported Friday morning. Overnight, air raid sirens were going off over much of Ukraine, the network also reported, and in addition to the capital Kyiv blasts were heard in the southern city of Kherson, the eastern city of Kharkiv, and in the western city of Ivano-Frankivsk.

The Russian Defense Ministry said the ship sank in a storm while being towed to a port. Russia earlier said the flames on the ship, which would typically have 500 sailors aboard, forced the entire crew to evacuate. The crew was evacuated to other ships in the area, according to the ministry.

The Moskva had the capacity to carry 16 long-range cruise missiles, and its removal reduces Russia’s firepower in the Black Sea. It’s also a blow to Moscow’s prestige in a war already widely seen as a historic blunder. Now entering its eighth week, the invasion has stalled amid resistance from Ukrainian fighters bolstered by weapons and other aid sent by Western nations.

During the first days of the war, the Moskva was reportedly the ship that called on Ukrainian soldiers stationed on Snake Island in the Black Sea to surrender in a standoff. In a widely circulated recording, a soldier responded: “Russian warship, go [expletive] yourself.”

Ukraine and its supporters consider it an iconic moment of defiance. The country recently unveiled a postage stamp commemorating it.

The news of the flagship overshadowed Russian claims of advances in the southern port city of Mariupol, where Moscow’s forces have been battling the Ukrainians since the early days of the invasion in some of the heaviest fighting of the war — at a horrific cost to civilians.

A Russian defense ministry spokesman, Major General Igor Konashenkov, said Wednesday that 1,026 Ukrainian troops surrendered at a metals factory in the city. But an adviser to Ukraine’s interior minister, Vadym Denysenko, rejected the claim, telling Current Time TV that “the battle over the seaport is still ongoing today.”

The stunning Russian loss at sea means that Russia has now suffered damage to two key naval assets since invading Ukraine, the British defense ministry said, the first being Russia’s Alligator-class landing ship Saratov on 24 March. Both events, it surmised, will likely lead Russia to review its maritime posture in the Black Sea.