military machine vs peacekeeping mission

military machine and peacekeeping mission both are nouns.

Word	Noun	Adjective	Verb	Adverb
military machine	Yes	No	No	No
peacekeeping mission	Yes	No	No	No

military machine (noun)	peacekeeping mission (noun)
the military forces of a nation	the activity of keeping the peace by military forces (especially when international military forces enforce a truce between hostile groups or nations)