This is the 7254th most frequent Russian word.
военную
"Военную" translates to "military" (as an adjective in feminine accusative form).
In this sentence, 'военную' modifies 'угрозу,' referring to a threat of a military nature.
Нам удалось избежать военную угрозу.
We managed to avoid a military threat.
The adjective 'военную' is used to describe 'академию,' specifying that it is a military-related academy.
Я учусь в военную академию.
I study at a military academy.
Here, 'военную' describes a type of operation, indicating the military nature of the activity.