What key factor determines the duration of classification for information?

The duration of classification for information is primarily determined by the value of that information to potential adversaries. Information that holds significant value to foreign entities, such as military capabilities, intelligence sources, or critical technologies, may have a longer classification duration to prevent it from falling into the wrong hands. The rationale behind this is that the exposure of such information could compromise national security or give adversaries an advantage. Therefore, the assessment of potential risks associated with the disclosure of sensitive information plays a crucial role in deciding how long it should remain classified.

While other factors such as complexity, cost, and relevance to current events may influence classification decisions in various contexts, they do not predominantly dictate the duration of classification like the value of the information to adversaries does.