I remember vividly the Russian tanks leaving Afghanistan at night as a defeated world power. It was more denigrating than the Biden escape last August. Massive losses to a band of locals but armed with Stinger missiles against helicopters and tanks.
Ukraine has leaky borders with NATO and other countries and the attack is emboldening the Ukrainians as nothing else can. Thus Putin in his grand arrogance, some say insane visions, has grossly failed to see this. The US had this in Vietnam and hopefully has remembered that locals even poorly armed, can blend in and destroy a major army.
This will potentially become such a swamp for Putin, especially when losses start to mount. He has claimed no Russian losses but viewing Russian tanks destroyed by UK provided anti-tank weapons leads one to wonder. If Ukrainians are ready to fight, then weapons for such a war are readily available.
The biggest risk is the insanity of nuclear weapons, but then we may have a homicidal maniac in the Kremlin.