The Shulchan Aruch (O.C. 566) writes that the bracha of aneinu added on fast days concludes with the words, "Ki atah Hashem ha'oneh b'eis tzarah l'amo Yisrael." The Vilna Gaon on the spot comments that in our gemara and in the Rambam the text of the bracha is missing the final two words and concludes, "...Ha'oneh b'eis tzarah." This is the nusach found in our siddurim as well. (It would be interesting to research early siddurim and gemaras and see if historically the two nuscha'os are both represented.)
The Aruch haShulchan is convinced that the nusach found in the SA is correct and goes so far as to say that the siddurim should be amended to match. His reasoning is as follows: If you look at the conclusion of other brachos that surround aneinu, they all mention Yisrael in their conclusion -- "Rofei cholei amo yisrael," "Go'el yisrael." Why should aneinu be any different?
I'm a little confused. While it's true that the two brachos he uses as examples end with references toYisrael, many of the other brachos nearby don't, e.g. "Chonein hada'as," "Harotzeh b'teshuvah," Chanun hamarbeh lisloa'ach." We don't say, "Harotzeh b'teshuvas Amo Yisrael," or "Chanun ha'marbeh lisloach l'Am Yisrael." Perhaps aneinu was written to match the pattern of these brachos.
This of course begs the question of why some brachos like refa'einu end with a reference to Klal Yisrael and other brachos do not. I don't have a good answer -- maybe one of you has an idea?