hi,
Please note I'm not a teacher nor a native speaker;
I'm unable to answer why some people might insist on that distinction it could be as Tdol says. I think there is a subtle difference in implicature.[STRIKE] An invasion is an act of aggression; but[/STRIKE] not every act of aggression is an invasion. An invasion also implies entering the invaded country mainland. So I think in some context it could be justified.
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afterthought
This has to do with perceptions of history. I imagine aggression is used because it sounds less serious than invasion. It's a form of euphemism, just as people sometimes use conflict instead of war.
I'm not sure if I could fully agree with that. We would talk about "an invasion of Normandy" but I don't think that anyone would call it "an act of aggression". Taking that to consideration it rather sounds more serious than invasion.
now I confused even myself
Is an invasion inherently an act of aggression ? Can one think of aggression as superordinate of invasion ?
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Another afterthought;
I'm sorry for a bit scattered answer but the question really get me thinking. After checking BNC for examples and reading two articles on Wikipedia about
invasion and
war of aggression it seems to me that there is a difference in the way the terms are used in the context of military operation.
after wiki on invasion :
The term does not imply the presence or lack of justification for the action, and the morality or immorality of a military operation does not determine whether it is so termed.
Whereas aggression implies the lack of justification.
So long as it is a matter of perceptions of history I definitely wouldn't say that it is used as an euphemism. I would even be inclined to say that the insistence of using
aggression instead of
invasion in the context of Japan military operation during the WWII is a form of admission of wrongdoing.
Cheers