MTDB is a Mine Threat Database, a centralized, structured repository of information about mine threats. The term “database” indicates a live, queryable collection that stores details such as mine types, emplacement patterns, detection and neutralization signatures, environmental considerations, and historical encounter data. In AMCM operations, this data supports planning and risk assessment by allowing crews to pull up area-specific threat information, inform route and sensor choices, and tailor tactics to reduce exposure. The other wording options don’t reflect the formal data-management idea of a searchable, organized store of threat information, which is why Mine Threat Database is the best fit.

Width sets how many mines you place across the field, based on each mine’s activation radius. Each mine creates an actuation circle around it, and to keep these zones from interfering with one another, the spacing across the width must be at least the diameter of that circle. So, the width essentially fixes the number of mines along that dimension to avoid overlapping actuation circles. The depth range relates to how far the field extends vertically, and the material of mines is a separate parameter, not determined by width.

NWP 3-15 is the publication that establishes the doctrine for Naval Mine Warfare. It defines the concepts, methods, and coordination for both offensive and defensive mine operations and the measures used to counter them. That focus is why it’s the best answer. The other topics correspond to different areas of warfare or ship operations, not the specific mine warfare doctrine covered by this publication.

In AMCM depth classifications, Very Shallow Water is defined as depths roughly from 10 to 40 feet. This range sits between the extremely shallow intertidal areas and the deeper nearshore zones, making it a distinct operating environment. Within this band, mine countermeasure assets can typically operate from nearby vessels or shore-based platforms, and sonar and other sensing methods still perform effectively, while factors like tides, waves, and sediment movement remain significant considerations for planning and safety. Depths below 10 feet are generally treated as an even more restricted, extremely shallow/intertidal zone, where operating conditions and procedures differ from the nearshore clearance work characteristic of Very Shallow Water. Once you exceed about 40 feet, you move into a deeper-water category, which has its own set of operational considerations and equipment requirements, distinct from Very Shallow Water.

Minesweeping is carried out using two broad approaches: mechanical sweeping and influence sweeping. Mechanical sweeping involves gear that physically interacts with mines along the path—such as tow devices that cut mooring lines or otherwise disable or remove mines, creating a safe corridor for ships to pass. Influence sweeping uses devices that generate fields or signals to mimic the presence of a vessel, triggering mines at a distance so they can be neutralized without contact. Magnetic and acoustic sweeps are specific kinds of influence sweeping, not separate broad methods, so the two main methods are mechanical and influence.