listening post

American  

noun

1. Military. a post or position, as in advance of a defensive line, established for the purpose of listening to detect the enemy's movements.

2. any foreign country or city viewed as a source of intelligence about an enemy or rival nation or one that is a potential enemy.

3. any concealed position maintained to obtain information.

   The government had listening posts to keep informed of revolutionary activities.

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listening post British  

noun

1.  LP.  military a forward position set up to obtain early warning of enemy movement

2. any strategic position or place for obtaining information about another country or area

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Etymology

Origin of listening post

First recorded in 1915–20