PART D: ANALYZE OBSTACLES, BARRIERS, AND OTHER DEFENSES
1. Obstacles, barriers, and other defenses are normally of a temporary or
semi-permanent nature, however, they can be found in permanent positions,
i.e., Berlin Wall, Maginot line, etc.
2. An obstacle or barrier is an obstruction that stops, delays, or diverts
Obstacles may be natural: deserts, mountains, steep slopes,
rivers, streams, gullies, swamps, heavy woods, jungle, deep snow, and such
manmade features as cities, towns, embankments, and canals; or they may be
artificial: demolished bridges, road craters, abatis artificially flooded
areas, minefields, contaminated areas, barbed wire entanglements, antitank
ditches, and log, steel, and concrete structures. The quantity and types of
artificial obstacles constructed are limited only by the time, labor,
ingenuity of the constructing unit.
The nature of the principal enemy
threat-infantry, armor, mechanized, airborne, airmobile, amphibious, or any
combination thereof-determines the character of the obstacles designed to
impede both armor and infantry are more effective than either antimechanized
or antipersonnel obstacles employed separately. The following subareas are
examples of the various types of obstacles, fortifications, and defenses you
may encounter on imagery.
Regular patterns of the obstacles and their shadows are the most
helpful recognition factors.
a. Minefields are extensively used by modern armies.
Aside from the
traditional method of hand emplacement, they have developed mine laying
equipment and techniques that include helicopter-dropped mines, armored
tracked minelayers, and mine-laying trailers.
The identification of
minefields from aerial may be very difficult especially when proper
camouflage discipline is maintained. Minefields are usually detected by--
(1) Spoil marks.
(2) Regular spacing and regular width.
(3) Distributed growth of vegetation.
(4) Tracks along edge of minefield.
(5) Convergency of tracks to "safe" lanes.
(6) Parched grass over buried mines.
This applies to regularly constructed antipersonnel and antitank
minefields. Scattered mines are almost impossible to detect. There
are no known conditions which create imagery effects similar