fate of a nation; national crisis; life-or-death for a nation
A formal, weighty term used in political or historical contexts to describe a nation's survival or existential crisis.
This war is a crisis of national survival.
A decision that will determine the fate of the nation is required.
存亡 alone means 'existence or extinction' and is used in broader contexts, while 国家存亡 specifically refers to a nation's fate.
国家 simply means 'nation' or 'state'; 国家存亡 adds the grave nuance of survival or crisis.
Compound of 国家 (nation) and 存亡 (existence or extinction). The exact historical derivation is uncertain, but the term is conventionally associated with grave national circumstances.