Escalation is the phenomenon of something getting more intense step by step, for example a quarrel, or, notably, military presence an nuclear armament during the Cold War. (Compare to escalator, a device that lifts something to a higher level.) The term is often said to be originally coined by Herman Kahn in his 1965 work On Escalation. While the OED records escalatory first used in that work, escalation is recorded as early as 1938.