The cost of war — on veterans’ health and taxpayer wallets — will loom a little larger in the new year. The Department of Veterans Affairs will issue a final rule to claim adjudicators to presume three more diseases of Vietnam veterans, including heart disease, were caused by exposure to Agent Orange. The rule, expected to be published soon, will make almost any veteran who set foot in Vietnam, and is diagnosed with Parkinson’s disease, B cell leukemia or ischemic heart disease (known also as coronary artery disease) eligible for disability compensation and VA medical care. The exception would be...