The federal government's role in providing health care to the nation's veterans can be traced back to World War I. The VA provides health care and health-related services through the Veterans Health Administration (VHA). VHA's primary mission is to provide health care services to eligible veterans and some family members. The VHA is also statutorily required to conduct medical research, to train health care professionals, to serve as a contingency backup to the Department of Defense (DOD) medical system during a national security emergency, and to provide support to the National Disaster Medical System and the Department of Health and Human Services (HHS) as necessary. This book provide information about veterans' health care.