Definition: In this task, a passage will be given and the goal is to identify an event from the passage. An event is defined as a single word representing something that happened, is happening, or may happen. An event can be factual or hypothetical, positive or negative, certain or uncertain. While most events are based on verbs, an event can also be based on a noun (ex. storm, snow, rainfall) or a copula verb (is, was, been, etc.). The event must not be a pronoun or an adjective. For noun events with multiple words, use the last word in the phrase as event.
Input: Passage: The PDPA's so-called Saur (April) Revolution marked the beginning of what they termed a "class struggle" between "feudals and workers" in order to inprove the living conditions of the common Afghan. Instead due to internal power struggles and badly implemented reforms the PDPA stirred up popular armed uprisings which led to the invasion of Afghanistan by the then Soviet Union in December 1979.

Revolution