The West should prepare for the collapse of Russia within the next four or five years, a former US general has warned.
Ben Hodges, who was general of the US Army in Europe and served in Iraq and Afghanistan, made the prediction as Ukrainian forces continue to make huge gains in their war against Russia.
Last month, Gen Hodges said exhausted Russian troops could crack by the end of this year.
Ukraine has managed to recapture Russian-occupied areas in the Kharkiv region.
Significant quantities of weapons and munitions were left behind as Moscow hastily withdrew its troops to prevent them from being surrounded.
Hodges told Times Radio on Monday: "We may be looking at the collapse of the Russian Federation as it is over the next four or five years.
"We were not prepared for the collapse of the Soviet Union [in 1991]. We need to be prepared for this possibility."
Explaining why Russia could break up, he said: "The military has been exposed, the massive amounts of corruption I think are going to become increasingly intolerable for Russian citizens.
Watch: Ukraine reclaims Russia-occupied areas in the northeastern Kharkiv region
"The two key pillars of their industry, energy export and arms export, I think both of them are going to be suffering."
Referencing Ukraine's recent territorial gains against Russian president Vladimir Putin's forces, Hodges said: "The Russians have collapsed in so many places because they're exhausted, their logistics are exhausted, their officers have been killed.
"Most of them just don't have the will to fight.
The former head of the British Army, Lord Dannatt, said Ukraine needs “more and more” arms from the West to “keep the pressure up on Russia”.
He said Russian troops have “pretty much turned and fled” from the Kharkiv area, representing a “significant reverse” of their position.
Russia has admitted withdrawing their troops, but claimed it was a tactical decision to enable them to "regroup".
“We are witnessing some incredible scenes,” Lord Dannatt told Sky News on Monday.
“Although the Ukrainians have made significant advances, there’s a lot of their country still in Russian occupation. So there’s a long way to go.”
Lord Dannatt said Russia was responding to Ukraine’s recent success in a “typically heavy-handed way”, and “blindly lashing out” by targeting the country’s power supplies.
Ukraine's president, Volodymyr Zelensky said Russia is trying to "deprive people of light and heat" by causing power cuts across the east of the country in revenge for the Ukrainian counter-attack.
In Kharkiv, the few pedestrians who could be seen outside on Sunday night used torches or mobile phones to guide them through darkened streets following the bombardment of a power station on the city’s western outskirts.
Lord Dannatt said “They (Russian officials) know that they’ve had a significant reverse on the battlefield, so they’re lashing out in other ways to try and restore their position.
“The resistance and the attitude that you’re seeing from the Ukrainian people is, ‘Yes, no, we don’t like the darkness, we don’t like the lack of water, but we will win through, they will not break our spirit’.
“And I think that is the other critical issue. Morale in Ukraine and morale amongst the Ukrainian forces is sky-high.”
Watch: 'No end in sight' to war in Ukraine, warns minister