The sunken Russian warship Moskva, which Ukraine says it destroyed in a missile strike, may have been carrying nukes when it went down, experts warn — as Russian state TV ominously declared that World War III has begun.

Russia suffered a massive blow when the flagship of its Black Sea fleet was targeted Thursday and went down off Sevastopol as it led Moscow’s naval effort in the seven-week conflict.

Now, several Ukrainian experts have raised the possibility that the 12,500-ton Moskva — the largest Russian warship to be sunk during active service since World War II — could have been carrying nuclear weapons.

Mykhailo Samus, deputy director of the Lyiv-based Center for Army, Conversion and Disarmament Studies, said the Moskva could have been carrying two nuclear warheads, East2West News reported.

However, the expert said they would have been in a “protected place” that would have prevented them from being damaged in the explosion, according to the news outlet.

Still, the fear of the ship’s weaponry comes weeks after defiant Russian President Vladimir Putin placed his country’s nuclear weapons on high alert following the start of the invasion.

The Kremlin’s main mouthpiece, Dmitry Peskov, also warned last month that Russia would use nukes if Putin suspects an “existential threat.”

The downing of its Black Sea flagship has already been described as a huge loss for the invading country.

In Washington, Pentagon spokesman John Kirby said Thursday he was unable to verify either version, but stressed that the ship’s sinking has dealt a “big blow” to the Russian fleet.

Meanwhile, Andrii Klymenko, editor in chief of Ukraine’s BlackSeaNews portal, called for an urgent international investigation into whether the Moskva was carrying nuclear weapons.

“Friends and experts say that there are two nuclear warheads for cruise missiles on board the Moskva,” he said, according to East2West News.

“Where are these warheads? Where were they when the ammunition exploded?  Where is the point on the map, the coordinates?,” Klymenko asked.

Ukraine’s Defense Express online news outlet also cited the possibility that the warship may have sunk with dangerous nuclear warheads.

“The Moskva missile cruiser, which overturned and began to sink after being hit by R-360 Neptune missiles, is a carrier of nuclear weapons,” it said in a report.