A senior U.S. defense official said on July 22 that Washington believes Russia is sustaining hundreds of casualties every day in its war in Ukraine and has lost thousands of lieutenants and captains since the start of the invasion.
In addition to the lieutenants and captains killed, hundreds of colonels and many Russian generals had been killed as well, Reuters quoted the officials as saying on condition of anonymity.
"The chain of command is still struggling," the official said.
CIA Director William Burns on July 20 said the United States estimates that Russian casualties in Ukraine after almost five months of war have reached around 15,000 killed and likely 45,000 wounded, adding that Ukrainian armed forces have also endured significant casualties.
Russia classifies military deaths as state secrets and has not updated its official casualty figures frequently during the war. On March 25 it said 1,351 Russian soldiers had been killed.
The Ukrainian government last month said that 100 to 200 Ukrainian troops were being killed daily.
The official also said Washington believed Ukraine had destroyed more than 100 "high-value" Russian targets inside Ukraine, including command posts, ammunition depots, and air-defense sites.
The United States has provided $8 billion in security assistance to Ukraine since the war began, including $2.2 billion in the last month.
Earlier this week, the Pentagon said it would provide Ukraine with four additional high-mobility artillery rocket systems in the latest weapons package.