The official said that there are about seven Russian ships in that area, including several warships, a minesweeper and a couple landing ships.

By contrast, the official said the US did not see indications that ships in the Black Sea were firing on Odesa, as they had done days ago.

The officials said the US assesses that the Russians have about 21 ships in the Black Sea, including about a dozen surface combatant warships and some landing ships that carry troops.

According to the official, Russian ground forces are still largely stalled outside Kyiv - with troops still about 30 kilometers (19 miles) northeast of the city, and 15 kilometers (9 miles) northwest of the city.

The official spoke on condition of anonymity to provide the US military assessment.

More broadly, the defense official said the US continues to see Russia struggling to get food and fuel to its force, and has been seeing indications that some troops don't have proper cold weather gear and are suffering frostbite.

The food and fuel shortages have been persistent logistical and supply problems since the early days of the war.

The official said there also are indications that Russia is exploring ways to resupply troops and is considering bringing in reinforcements, but so far there has been no active moves seen to do either.

There also are indications that Russian has used a significant number of its precision guided munitions, particularly its air-launched cruise missiles, and is exploring ways to resupply those weapons, the official said.