What determines the validity duration of a Declaration of Security (DoS)?

The validity duration of a Declaration of Security (DoS) is primarily determined by changes in the Maritime Security (MARSEC) levels. The MARSEC levels are established by the U.S. Coast Guard and other maritime security authorities, dictating the necessary security measures that vessels and ports must implement based on perceived threats. When MARSEC level changes occur, the security situation may evolve, necessitating a review and potential revision of security plans, including the DoS.

A DoS is meant to ensure that security measures are appropriate for the current threat level. If the MARSEC level fluctuates—whether it is raised due to heightened risk or lowered in response to a decrease in threat—the existing DoS may no longer adequately address the security needs, thus affecting its validity. Consequently, this establishes a direct link between MARSEC levels and the ongoing relevance of the DoS, which is why the correct answer centers on changes in MARSEC level.