U. S. customs laws help regulate the conduct of business, protect U. S. citizens from harmful diseases, and protect U. S. crops and livestock from damaging foreign diseases, infections, and other pests. The customs laws also reflect U. S. policy on environmental issues. The United States Customs Service is the agency with primary responsibility for protecting the nation’s borders. It has an extensive air, land, and marine interdiction force and with an investigative branch supported by its own intelligence resources. Among its areas of responsibility, the U. S. Customs Service is charged with overseeing the importation of goods into the country.