Officials in the United States have suggested that Russian President Vladimir Putin is becoming "increasingly frustrated" with his invasion of Ukraine.
The conflict has entered its sixth day, with some 5,700 Russian soldiers dead so far, according to Ukraine.
The General Staff of the Armed Forces of Ukraine said it had also taken 200 prisoners of war.
Russia's economy is also struggling in the wake of sanctions imposed by western powers, with the value of the rouble plummeting and interest rates hitting 20%.
The situation remains on a knife edge, with concerns about Putin's state of mind and what he might do next.
He is reportedly frustrated and "directing unusual bursts of anger at people in his inner circle" over Russia's military campaign, NBC News reports.
The US media outlet cites intelligence agency sources who believe the president's frustrations will lead him to "doubling down on violence".
“This is somebody that’s clearly been caught off guard by the size of the Ukrainian resistance,” Mark Warner, chairman of the Intelligence Committee, told MSNBC.
“He has isolated himself. He’s not been in the Kremlin very much. ... You’ve got less and less inputs, and these inputs are from sycophants.
"I do worry that he’s been backed into a corner. I do worry that there is no obvious exit ramp.”
Intelligence agencies are closely monitoring Putin for what actions could emanate from his altered pattern of behaviour.
One diplomat from the West said: "The main concern is the information he’s getting and how isolated he is.
"The isolation is a really big concern. We don’t believe he has a realistic understanding of what’s going on.”
Meanwhile, former CIA Director John Brennan said Putin "is no longer the same cold-blooded, clear-eyed dictator that he was in 2008".
NBC reports how Mr Brennan believes the Ukrainian invasion was "a bad, bad miscalculation on Putin’s part".
He said: "He’s never faced something like this before. I’m sure he’s lashing out at advisers, ministers and others — there may be an emotional spiral here.
"He’s suffered two black eyes, a bloody nose and a series of punches. He is being crippled on the battlefield and the financial front, and he has no good options.”
Alexander Vershbow, a former ambassador to Russia and deputy secretary general of NATO from 2012 to 2016, said the invasion is "faltering".
“The next stage may be the scorched-earth tactics that we saw in Chechnya and Syria, which would mean much more death and destruction,” Mr Vershbow said.
