Russian flagship sinks after Kyiv claims missile hit

Russia's Black Sea flagship sank Thursday after an explosion and fire that Ukraine claimed was a successful missile strike -- as the Kremlin accused Kyiv of targeting its citizens in sorties across the border.

The guided missile cruiser Moskva had been leading Russia's naval effort against its neighbor in the seven-week conflict, in which civilian killings have sparked accusations of genocide.

Russia's defence ministry said the blast on the vessel was the result of exploding ammunition and added that the resulting damage had caused it to "lose its balance" as it was being towed to port.

"Given the choppy seas, the vessel sank," the Russian state news agency TASS quoted the ministry as saying.

On the Ukrainian side, Odessa military spokesman Sergey Bratchuk said the ship had been hit by domestic Neptune cruise missiles.

In Washington, Pentagon spokesman John Kirby said he was unable to verify either version, but stressed that the sinking of the Moskva dealt a "big blow” to the Black Sea fleet.

Meanwhile, in Ukraine's east and south, civilian evacuations had been set to resume Thursday, Deputy Prime Minister Iryna Vereshchuk said, after a day-long pause that Kyiv blamed on Russian shelling.

More than 4.7 million Ukrainians have fled their country in the 50 days since Russia invaded, the United Nations said.

The flagship fire came after the United States unveiled an $800-million military aid package that includes heavy equipment specifically tailored to help Ukraine repel the Russians in the east, from howitzers to armoured personnel carriers and helicopters. 

Following its pullout from northern Ukraine earlier this month after failing to take the capital, Russia is refocusing on the east, with Kyiv warning of bloody new clashes to come in the Donbas region.

Seizing Donbas, where Russian-backed separatists control the Donetsk and Lugansk areas, would allow Moscow to create a southern corridor to the occupied Crimean peninsula. 

But rain that has been battering the region for days could favour Ukraine in its fight against invading Russian forces, a senior Pentagon official said Thursday.

"The fact that the ground is softer will make it harder for them to do anything off of paved highways," said the official, who spoke under condition of anonymity.

Moscow's Black Sea fleet has been blockading the besieged southern port city of Mariupol, where Russian officials say they are in full control.