This system is called a junta.
A junta is a Spanish word that is used for military dictatorships.
When a government is overthrown, the group or coalition that forms and takes control is called junta. If military is involved in the attack, the group is called military junta. The system is usually authoritarian, meaning allowing its own rule only.
Some examples of countries ruled once by juntas are: Greece, South Vietnam, El Salvador, Myanmar.
The word junta comes from the Latin jungere which means to join.
