The flagship of Russia's Black Sea Fleet, the Moskva, lies at the bottom of the sea.
Ukraine says the Russian warship, which was sailing off the coast of Odesa, was destroyed Thursday by one of its missiles.
A US official has supported Ukraine's version of events, saying they believe the Moskva was downed by a Ukrainian Neptune anti-ship missile.
Still, Russia's defence ministry has not confirmed this. They said the warship sunk while being towed to port, following a fire onboard, which involved ammunition stored in the hull.
In any case, the Moskva is now out of action - for good. But what impact, if any, will this have on the war in Ukraine?
Loss of defensive firepower
The Moskva, equipped with surface-to-air missiles, provided long-range and mobile air defence for the whole of Russia's fleet in the Black Sea. It protected cruisers, frigates, missile corvettes and amphibious landing ships capable of carrying thousands of troops.
Without the Moskva's defensive firepower, this fleet will be more vulnerable to attack, especially from the Ukrainian Air Force.
Nevertheless, Russia has powerful air defence systems deployed in Crimea, which it seized from Ukraine in 2014. These can defend the fleet against attack as it operates in the area.
**Can the Moskva be replaced? **
Russia will not be able to replace the capabilities of the Moskva any time soon. It only has two other ships of the same class - the Marshal Ustinov and the Varyag - which serve with Russia's Northern and Pacific fleets respectively.
To reach the Ukrainian theatre, both would need to pass through the Bosphorus into the Black Sea. The waterway between Istanbul is controlled by Turkey, which says it will not let warships from any state pass through.
"When Turkey is not a belligerent in the conflict, it has the authority to restrict the passage of the warring states’ warships across the straits," Mevlut Cavusoglu, Foreign Minister of Turkey, said in February.
How good was the ship anyway?
The Moskva was old and outdated. Designed in the 1970s during the Cold War, it was built to destroy US aircraft carriers and had been on the waves for nearly four decades.
Although the warship had undergone an extensive re-fit, returning to operational status in 2021, some of its hardware remained outdated, according to Britain's Ministry of Defence.
Some 500 Russian sailors were crewed on the Moskva when the blaze broke out. Although Russia successfully evacuated many onboard the ship to the port of Sevastopol in Crimea, Ukraine has suggested there were likely to have been fatalities.
Neither Russia nor the US has commented on the number of possible casualties or if there are any at all.
The blow to Russian pride
The loss of Russia's flagship is a bitter blow for Russia, and embarrassing internationally. Although old, it was a symbol of Russia's dominance in the sea and of the country's military prowess.
If the ship was destroyed by a Ukrainian missile as both Ukraine and the US claim, it would be the biggest Russian warship to be lost since World War Two, when German bombers crippled the Soviet battleship Marat in Kronshtadt harbour.
The sight of the Russian ship sinking "is a major propaganda victory" for Ukraine, said an ISW assessment. Western diplomats and experts suspect heads will roll in Moscow over the loss of the ship.
**Was a role planned for the Moskva? **
Analysts have suggested that the Moskva was going to play a role in a potential Russian amphibious assault of the Ukrainian port of Odea, which had not yet happened due to resistance from Ukrainian forces.
The odds of this taking place are now seen as lower in some quarters, and this could allow Ukraine to redeploy some of its troops elsewhere.
Yet this is only one train of thought. The extent to which this was Russia's plan is not clear.
Will the sinking of the Moskva change the outcome of the conflict?
The war in Ukraine is primarily a ground war. The seas have so far not played a big role in the conflict.
US officials have said that, while the sinking of the Moskva will have a symbolic impact, potentially boosting Ukrainian morale at the expense of Russia's, it will not have a major impact on the course of the conflict.
Speaking to Reuters, one US official added that Russia had only used the ship on limited occasions, such as resupplying troops in the south and carrying out occasional strikes.
Yet Britain's Ministry of Defence has said the loss will likely cause Russia to review its naval posture in the Black Sea.
After the alleged missile strike, Russia's ships pulled further away from the Ukrainian coastline by about 80 nautical miles, although at this distance they can still strike Ukraine.