Final answer:
The country invaded by the US in Operation Urgent Fury was Grenada, where US forces responded to a Marxist coup and concerns of a Communist-aligned government.
Step-by-step explanation:
Operation Urgent Fury: Invasion of Grenada
The country that was invaded by the US in Operation Urgent Fury was Grenada. On October 25, 1983, around 7,000 US soldiers participated in this invasion. This military action was a response to a coup d'état by Marxist rebels who had seized control of Grenada's government, which concerned the United States due to the possibility of a Communist government aligned with Cuba and the Soviet Union being established. The invasion resulted in the overwhelming defeat of the Grenadian and Cuban forces by the US military, leading to a shift in government that was more friendly to US interests.