Refers to a form of government where the military holds supreme power, often through a junta or a single military leader.
That country was under a military dictatorship for many years.
軍事政権 is a military regime or junta, often the ruling body itself, while 軍部独裁 emphasizes the dictatorial aspect of military rule.
Compound of 軍部 (military authorities) and 独裁 (dictatorship).