air defense
Military and civil protection against aerial attack. Common in compounds like 防空壕 (air-raid shelter) and 防空演習 (air-defense drill).
During World War II, air-raid shelters were used in many cities.
The government announced the strengthening of air defense systems.
In the middle of the night, an air-raid siren suddenly sounded.
The government strengthened the air-defense system along the border region.
The enemy aircraft broke through the air-defense network and approached the capital.
air defense identification zone; ADIZ
man-portable air-defense system; MANPADS