He made the same mistake that the shrub and dick(less) made when they invaded Afghanistan, they wanted an easy victory. They forgot the old adage that Afghanistan is where empires go to die. The Romans, Alexander the Great, Britain, France and of course Russia and The Soviet Union all invaded Afghanistan and failed. Putin's dream of restoring the Soviet Union rested on an easy invasion of Ukraine.
Problem being that like other former Soviet State, Ukraine did NOT want to part of Pooty's Empire. He having convicts for troops and his war is very unpopular at home