Identify one indicator of a potential terrorist threat.

Unusual activity or behavior around critical infrastructure can be a significant indicator of a potential terrorist threat. Critical infrastructure refers to essential assets that are crucial for the functioning of a society, such as transportation systems, utilities, and communication networks. When individuals exhibit suspicious behavior—such as taking photographs, loitering, or engaging in reconnaissance near these sites—it could indicate that they are gathering information for a possible attack.

Such behavior stands out against normal activity, which typically aligns with routine operations and the presence of legitimate workers or visitors. Identifying these anomalies becomes a key part of threat assessment, allowing emergency responders to mitigate risks before they escalate.

In contrast, uniformed individuals at public events may simply be security personnel performing their roles, and increased police presence could indicate heightened vigilance or a response to an event rather than a direct threat. Similarly, frequent public gatherings and rallies are common occurrences and do not inherently signify any malicious intent. Thus, unusual behavior in close proximity to critical infrastructure is a clear warning sign that should raise concern and prompt further investigation.