From the readings, what type of nonliteral collection do you think is the most i

From the readings, what type of nonliteral collection do you think is the most important for strategic intelligence and combat/tactical intelligence? First define what nonliteral intelligence covers and includes, then provide your response.
Readings:
https://irp.fas.org/nsa/almanac-elint.pdf
https://www.nsa.gov/portals/75/documents/about/cryptologic-heritage/historical-figures-publications/publications/technology/elint.pdf?ver=2019-08-07-124409-477
Chapter 12 from: https://lgapi-us.libapps.com/ld.php?er_attachment_id=958148&site_id=1192&request_id=68584135&token=XPguAmTLdxMpdvb3tXXQ5hzQmhdXht32wj3hKF9y
https://www.bbc.co.uk/history/worldwars/wwtwo/enigma_01.shtml