Under rules to be proposed this week, the Department of Veterans Affairs plans to add Parkinson’s disease, ischemic heart disease and hairy-cell leukemia to the growing list of illnesses presumed to have been caused by Agent Orange, the toxic defoliant used widely in Vietnam.

The proposal will make it substantially easier for thousands of veterans to claim that those ailments were the direct result of their service in Vietnam, thereby smoothing the way for them to receive monthly disability checks and health care services from the department.

The new policy will apply to some 2.1 million veterans who set foot in Vietnam during the war, including those who came after the military stopped using Agent Orange in 1970. It will not apply to sailors on deep-water ships, though the department plans to study the effects of Agent Orange on the Navy.