Russian President Vladimir Putin is being misled by advisers who are too scared to tell him how badly the war in Ukraine is going, the White House says.
Meanwhile British intelligence says Russian troops in Ukraine are demoralised, short of equipment and refusing to carry out orders.
Mr Putin is also not being told about the full impact of sanctions on the Russian economy, the White House said.
The Kremlin has not yet commented on the assessments.
White House spokesperson Kate Bedingfield said the US had information that Mr Putin “felt misled by the Russian military” and this had resulted in “persistent tension between Putin and his military leadership”.
“Putin’s war has been a strategic blunder that has left Russia weaker over the long term and increasingly isolated on the world stage,” she said.
Pentagon spokesman John Kirby called the assessments “discomforting” because an uninformed Putin could result in a “less than faithful” effort at ending the conflict through peace negotiations.
“The other thing is, you don’t know how a leader like that is going to react to getting bad news,” he said.
Ukrainian forces have begun attempts to retake some areas from Russia, which on Tuesday said it would scale back operations around Kyiv and the northern city of Chernihiv.
Jeremy Fleming, the head of the UK’s cyber-intelligence agency GCHQ, said the move added to indications Russia had “massively misjudged the situation” and had been forced to “significantly rethink”.
“We’ve seen Russian soldiers – short of weapons and morale – refusing to carry out orders, sabotaging their own equipment and even accidentally shooting down their own aircraft,” Mr Fleming said in a speech to the Australian National University in Canberra.
“And even though Putin’s advisers are afraid to tell him the truth, what’s going on and the extent of these misjudgements must be crystal clear to the regime.”
On the ground, US and Ukrainian officials say Russia is continuing to reposition forces away from Kyiv, probably as part of its effort to refocus on eastern regions.
By Correspondent.