countermine
noun
coun·ter·mine ˈkau̇n-tər-ˌmīn 
: a tunnel for intercepting an enemy mine
Example Sentences
Recent Examples on the Web Hahn described these countermine crafts, the most widely used version being the MK18, as a gateway to broader naval use of unmanned underwater systems. 
The Atlantic, 3 Sep. 2019 Depending on the mission modules installed onboard, the USS Jackson can perform anti-submarine warfare, anti-surface warfare and countermine warfare. Beth Nakamura, OregonLive.com, 8 June 2017
The Atlantic, 3 Sep. 2019 Depending on the mission modules installed onboard, the USS Jackson can perform anti-submarine warfare, anti-surface warfare and countermine warfare. Beth Nakamura, OregonLive.com, 8 June 2017 Word History
First Known Use
1548, in the meaning defined above