In warfare, recourse to deliberate destruction of the environment is frequently an integral part of military strategy. Such warfare involves the defoliation or destruction of forest trees, the pollution or craterization of cultivated fields, and destruction or diversion of water sources. By these means it is hoped to deny the enemy cover, food, and the life-support of the countryside, thus making it more difficult for him to mass for effective attack.
Geophysical weapons and weather modification techniques of warfare are in the experimental or research stages. Objectives include storm and rain production, stimulation of seismic earth shocks, ozone layer interference, production of tsunamis, creation of lightning, and other weather and environmental disturbances.
Environmental warfare techniques were used by the USA in Vietnam. In the period 1962-1968, 4,560,600 acres of forest land, representing 10% of the entire area of Vietnam, were sprayed with herbicides. These herbicides, such as Agent Orange, contaminate crops, have teratogenic effects on unborn children, and poison humans and animals. Plant cover can also be destroyed by the use of very large, bulldozer-driven Rome ploughs, and bombardment and artillery fire may also be used, deliberately or incidentally, to destroy the environment. Munitions create craters, which prevent the use of arable and timber land indefinitely, create breeding grounds for mosquitoes, accentuate soil run-off and erosion, and cause laterization of the land. Weather modification cloud-seeding has been used to increase rainfall to make roadways muddy and unusable; and land may be indiscriminately devastated by using electronic battlefield or systematic bombing techniques.