Why are human intelligence sources still needed when satellites and electronic surveillance exist?

While satellites and electronic surveillance provide essential data on military capabilities, troop movements, and industrial production, they cannot fully replace human intelligence (HUMINT).12

Technical means, such as imagery intelligence and signals intelligence, are highly effective at capturing "hard" data—such as the location of nuclear missiles or the "signature" of a submarine. However, these methods are limited in their ability to discern the subjective elements of statecraft. Only human sources can provide critical insights into the attitudes, motivations, and future intentions of foreign leaders, terrorists, or other nonstate actors.1324

Understanding these internal decision-making processes is vital for national security, as technical systems often cannot predict political shifts or the strategic rationale behind a government's actions. The reliance on machines alone can leave significant gaps in intelligence, as evidenced by the failure to prevent the September 11 attacks, where a lack of adequate human intelligence was identified as a contributing factor. Consequently, human agents remain indispensable for accessing the high-level political and strategic information that technology cannot reach.124