The ISPS Code is a comprehensive set of measures to enhance security of ships and port facilities, developed in response to threats after 9/11. It is an amendment to the SOLAS Convention and consists of mandatory security requirements and guidance. The ISPS Code applies to ships on international voyages over 500 GT as well as port facilities serving those ships. Its main objectives are to detect and respond to security threats by establishing roles and responsibilities and collecting/sharing security information according to three security levels: normal, heightened, and exceptional/imminent risk. Requirements for ships include Ship Security Plans, Ship Security Officers, and certain equipment. Requirements for ports include Port Facility Security Plans and Port Facility Security Officers.