Can someone explain the answer to the following question and give reasons from the tax code?

Aubrey Brown is a decorated veteran of the Vietnam War. As a result of his exposure to Agent Orange during the war, Aubrey developed lung cancer and is unable to work. He received $12,000 of Social Security disability payments in the current year. He reasons that the payments should be excluded from his gross income because the payments are compensation for the physical injury he suffered as a result of his service in the armed forces. Is Aubrey correct? Explain.