A forbidden method of warfare whose primary purpose is to spread terror among the civilian population.
Indiscriminate bombardment is one of the principal methods of terror.
For War on Terror, see War on Terror
Chapter 9, II. 6. a) attacks against the civilian population as such (including those intended to spread terror)
SAYAPIN Sergey V., “The Spread of Terror among the Civilian Population: A War Crime?”, in Asia-Pacific Yearbook of International Humanitarian Law, Vol. 2, 2006, pp. 196-225.