air defense by the use aircraft or missiles or artillery or electronic countermeasures

air defense by the use aircraft or missiles or artillery or electronic countermeasures

a line of defense consisting of a barrier of felled or live trees with branches (sharpened or with barbed wire entwined) pointed toward the enemy

a line of defense consisting of a barrier of felled or live trees with branches (sharpened or with barbed wire entwined) pointed toward the enemy