An amateur radio station may be used to communicate with:

Amateur radio stations are authorized to communicate specifically with other amateur radio stations, which the regulations refer to as 'stations operated under similar authorizations.' The purpose of the amateur service is for self-training, intercommunication, and technical investigations between amateurs. Communicating with non-amateur stations, such as military, commercial, or broadcast stations, is strictly prohibited unless explicitly authorized by the government during a declared emergency. Furthermore, you cannot communicate with 'any' station transmitting on amateur bands, because if an unauthorized pirate station transmits there, you are not permitted to reply to them.