China Maritime Studies Institute – Sea mines are a type of cheap, easy to produce naval weapon that can be used both offensively and defensively. They have played a huge tactical role and even a strategic role in many wars from ancient times to the present day. Sea mines have low production costs, and they are powerful, simple to use, easy to emplace, and difficult to remove. They are characterized by the long-term threat they can pose to ports and shipping lanes. Countering sea mines is relatively difficult and requires the expenditure of rather large resources by the side conducting mine countermeasure operations.