Here's how the Navy characterizes minehunting and minesweeping.
www.navy.mil/n85/miw_primer-june2009.pdf
21ST CENTURY U.S. NAVY MINE WARFARE
HUNT IF YOU CAN...SWEEP IF YOU MUST
Mine hunting provides a relatively high degree of certainty that an area of concern is mine-free or the risk of a mine strike has been minimized. It comprises five steps: detection, classification, localization, identification, and neutralization. Sonars are the primary means to detect and classify mine-like contacts. Identifying each contact as a mine or a “NOMBO” (Non-Mine/Mine-Like Bottom Object) can also be carried out by EOD divers and the Navy’s marine mammal systems, video cameras on mine neutralization vehicles, and laser systems. In this regard, advanced sonars on unmanned underwater vehicles offer good promise to enhance mine-hunting capabilities
A contact that is classified as mine-like must be identified as a mine or NOMBO and, if a mine, rendered safe before the Navy mine coun-termeasures commander, or the Coast Guard in a domestic mine crisis, can declare a route or area cleared. (As the Lead Federal Agency for maritime homeland security, the Coast Guard’s Captains of the Port are the only officials who can close and open U.S. ports in response to an emergency.) Depending on the accuracy of the location of the contact, the characteristics of the bottom (e.g., smooth or rough), sediment type, amount of clutter, and the depth of the water, among other factors, the process of reacquisition and identification of each mine-like contact can take several hours. EOD divers, marine mammals, and mine-neutralization systems are the Navy’s primary means for neutral-izing sea mines and underwater IEDs.
The two types of
minesweeping are mechanical and influence systems. Mechanical sweeping consists of cutting the tether of mines moored in the water volume or other means of physically damaging the mine, such as chain drags to cut control wires. Moored mines cut loose by mechanical sweeping must then be neutralized or rendered safe for subsequent analysis. Influence minesweeping consists of simulating the magnetic, electric, acoustic, seismic, or pressure signatures of a ship so that the mine fires.
Intelligence, surveillance, and reconnaissance of an adversary’s mining objectives and tactics are extremely important when influence sweep-ing, as is specific intelligence on the operation of a mine’s sensors, firing criteria, and any counter-countermeasures (e.g. ship counters and delay arming). Minesweeping is more risky to the sweeping platform than mine hunting and, when completed, generally leaves behind a higher residual risk to vessels that transit the swept area. To ensure as low a risk as possible, then, most mine countermeasures operational plans include both mine hunting and minesweeping
