Mines with ship - counters , arming delays and highly specific target signatures in mine fuzes can falsely convince a belligerent that a particular area is clear of mines or has been swept effectively .
A succession of vessels have already passed through safely .
Mines with ship - counters , arming delays and highly specific target signatures in mine fuzes can falsely convince a belligerent that a particular area is clear of mines or has been swept effectively because a succession of vessels have already passed through safely .