What security level requires heightened security measures?

Security Level 2 is the appropriate choice as it indicates a heightened security posture in response to an elevated risk of a security incident. This level signifies that there is a greater potential threat than would typically be encountered at Security Level 1, which is the baseline level where security measures are maintained under normal conditions.

At Security Level 2, additional measures are implemented to enhance security and prevent any potential threat from materializing. These measures may include increased personnel presence, more extensive surveillance, and additional access controls. The purpose of this heightened security is to mitigate risks and safeguard both personnel and assets against potential attacks or breaches.

In contrast, Security Level 3 would indicate a serious threat where security measures must be significantly intensified beyond those at Level 2. Additionally, Security Level 1 involves standard procedures without the increased vigilance required at Level 2. Security Level 4 is typically not used in standard maritime security schemas and indicates measures that are not part of the recognized levels in most frameworks. Thus, the response aligns with the established protocols that define appropriate actions during different security levels according to the perceived threat.