war vs military action

war and military action both are nouns.

Word	Noun	Adjective	Verb	Adverb
war	Yes	No	Yes	No
military action	Yes	No	No	No

As nouns, military action is a hypernym of war; that is, military action is a word with a broader meaning than war:

Other hypernyms of war include action.

war (noun)	military action (noun)
the waging of armed conflict against an enemy	a military engagement
a concerted campaign to end something that is injurious
an active struggle between competing entities
a legal state created by a declaration of war and ended by official declaration during which the international rules of war apply

war (verb)	military action (verb)
make or wage war