Countermines, a term used to refer to underground tunnels designed to attack an invading army's mining operations, has multiple antonyms that can be used to express the opposite meaning. Firstly, instead of countermines, one could use the term 'aboveground structures' to refer to buildings or fortifications that are constructed above ground. Another option could be 'surface defenses' which refers to military installations designed to repel enemy attacks on the ground level. Additionally, the term 'surface facilities' can be used to describe military bases, camps, and other installations that are built on the surface of the earth. Essentially, countermines' antonyms refer to structures and facilities that are above the ground rather than underground.