Putin isn’t going to stop with half of Ukraine - read what he’s written and hear what he’s said. The mistake in the past was not believing him.
Russia is pushing for a ceasefire in order t9 gain to time to rearm and rebuild their army - and they are doing both far faster than the West.
Politicians and the military Finland, the Baltics, Germany and others have warned us that we have only 5 years before Russia moves into to attack a NATO nation - again read what they have written and hear what they have said and believe them.
If we don’t help fight them in Ukraine we will have to fight them on our own soil.