The 1953 Iranian coup d'état was staged by the United State.
The 1953 Iranian coup was staged by the United State.
Are 1 and 2 mean exactly the same thing? Which one is more idiomatic: coup or coup d'état?
"Coup d'état" is a French expression dating back to the mid-1600s (although not with the same meaning until 1800) which has been adopted into English. Because it's been around for so long it should be no surprise that it has been shortened to simply "coup"; however both mean the same thing.
In general "coup d'etat" is more of a written word than a spoken word, possibly because English speakers are not always confident how to say it correctly (the final "t" is silent). It's fine to use either, assuming your audience is familiar with the expression. As with many "educated" expressions, particularly those borrowed from other languages, depending on the context "coup d'état" can sound either erudite or pretentious. i
Side note: You can also use the synonymous Swiss-German "putsch", at least in writing -- again because few English speakers know how to pronounce it correctly and may confuse it with "put" or "push".
Both versions are fine and mean the same thing. Coup is more commonly used than Coup d'etat.
The first mention in a newspaper article should be the full term: coup d'etat,the formal term from French, used in English.
It should not just be coup in English on the first mention in my opinion.
The English would be: overthrowing the government or overthrowing of the government
On the second mention, you can just use coup.