In the United States Department of Defense, Humanitarian Civic Assistance (HCA) is relief and development activities that take place in the context of an overseas military exercise, training or operation. Under the HCA program, U.S. military personnel participating in overseas deployments carry out humanitarian activities such as road and school construction, vaccination of children and animals, and well-digging. HCA programs are often executed with the involvement of host-country civilian and military personnel. U.S. National Guard or reserve units are involved in many HCA activities.