Which of the following is NOT one of the three levels of security under the ISPS Code?

The correct answer is based on the established framework of the International Ship and Port Facility Security (ISPS) Code, which defines three specific security levels that must be implemented in maritime security measures. These levels are Security Level 1, Security Level 2, and Security Level 3, each corresponding to different threat conditions and the required security responses.

Security Level 1 is the baseline level that indicates normal operations, where the risk of a security incident is low. Security Level 2 indicates a heightened risk where additional security measures are necessary, and Security Level 3 is instituted when there is a serious and imminent threat, requiring the most stringent security protocols.

However, the framework does not designate a Security Level 4, making it clear that the inclusion of such a level is extraneous to the ISPS Code's structured approach. This distinction clarifies the operational security measures that facilities and vessels must follow, aligning with the established norms to prevent and address potential threats in maritime environments. Therefore, the absence of a Security Level 4 from the ISPS Code confirms that the option provided is not aligned with the recognized security levels.