With Minnesota Gov. Tim Walz facing misleading Republican attacks on his service record in the Army National Guard, some political commentators are drawing comparisons to the “Swift Boat Veterans for Truth,” a GOP smear campaign where Vietnam veterans attacked the service record of 2004 Democratic presidential nominee John Kerry. Speaking to Politico in an interview, Bob Shrum, an adviser to Kerry, outlined how significant these attacks might be — and how to defuse them. When it came to Kerry, who received three Purple Hearts, a Silver Star and a Bronze Star, he said, “In the end, the attack d…