What is one of the criteria for establishing a Magnuson Act security zone?

The Magnuson Act security zone is primarily established in response to clearly expressed security threats. The act is part of a broader framework to ensure national security and to protect U.S. interests in maritime environments. When evaluating the need for a security zone, the presence of specific threats—be it from potential terrorist activity, environmental sabotage, or threats to critical infrastructure—guides the decision-making process. Establishing such a zone is intended to prevent incidents and ensure safety among maritime operations.

The other options, while they may pertain to maritime management and the usability of waterways, do not directly relate to the criteria necessary for establishing a security zone under the Magnuson Act. Hence, they don't play a role in the determination of the need for security measures.