How to say "reconnaissance" in Japanese

• 偵察ていさつCommon
  noun, suru verb, transitive verbCovers reconnaissance in its core sense of scouting: observing terrain, enemy positions, or movements from the field. This is the word for military reconnaissance, as when a unit scouts an area before an operation.
• 内偵ないていCommon
  noun, suru verb, transitive verbIts primary sense is secret or private investigation: covert inquiry into a person's or organization's activities, as by detectives or undercover officers. It fits 'reconnaissance' only in that covert-investigation sense, not for field scouting.

Use 偵察 for reconnaissance as scouting — observing terrain or enemy positions from the field; use 内偵 when reconnaissance means covert investigation, secretly inquiring into a person's or organization's activities.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

• 偵察ていさつscouting
• 内偵ないていsecret investigation