derived noun from escalate; in the figurative sense it is from 1938, in reference to the battleship arms race among global military powers.
1922, back-formation from escalator, replacing earlier verb escalade (1801), from the noun escalade. Escalate came into general use with a figurative sense of "raise" after 1959 in reference to the possibility of nuclear war. Related: Escalated; escalating.
An increase in the intensity or geographical scope of a war or diplomatic confrontation. For example, during the Korean War, some Americans urged escalation of the war through bombing of the People's Republic of China.