Russian military leaders are executing their own troops who try to retreat from a bloody offensive in Ukraine, the White House has claimed.
According to the US, some of the casualties suffered by Russia near Avdiivka, in eastern Ukraine, were "on the orders of their own leaders".
There has been a bitter battle for the frontline town for almost two weeks, with Russia thought to have suffered "significant losses".
Ukrainian estimates put the number of Russian dead at roughly 5,000. The Kremlin has not commented on the figures.
A Ukrainian army spokesperson said Russian troops were refusing to attack Ukrainian positions near Avdiivka because of heavy losses and that there had been mutinies in some units.
"Russia's mobilised forces remain under-trained, under-equipped and unprepared for combat, as was the case during their failed winter offensive last year," National Security Council spokesman John Kirby said in a briefing on Thursday.
He said that the Russian military "appears to be using what we would call 'human wave' tactics, just throwing masses of these poorly trained soldiers right into the fight."
"No proper equipment, no leadership, no resourcing, no support. It is unsurprising that Russian forces are suffering from poor morale," Mr Kirby added.
He continued: "We have information that the Russian military has been actually executing soldiers who refuse to follow orders.
"We also have information that Russian commanders are threatening to execute entire units if they seek to retreat from Ukrainian artillery fire."
Representatives from the Kremlin, the Russian defense ministry, and the Russian embassy to the United States did not immediately respond to requests for comment about the issue.
Russia's ambassador to Washington, Anatoly Antonov, in a comment on the Telegram messaging app, made no reference to the White House allegations.
Ukrainian officials said on Wednesday that Russian forces were disregarding heavy losses and pressing on with a drive to capture the eastern Ukrainian city of Avdiivka.
The United States has strongly condemned Russia's invasion of Ukraine and has been providing significant aid to Kyiv.
