The sacrifices that the two countries have been told they must make ARE to restore stability to the world economy
are
almost if not completely the opposite of each other.
不要語は、make ARE to restore~ のARE.
The sacrifices that the two countries have been told they must make to restore stability to the world economy
are
almost if not completely the opposite of each other.
構造は、
S The sacrifices that the two countries have been told they must make
不定詞 to restore stability to the world economy
V are
C almost if not completely the opposite of each other.
if not completelyがコンマで挟まれてたら、almost(ほとんど)とcompletely(完全に)の対比に気付けたかもしれない。
almost, if not completely, the opposite of each other.
名詞】【可算名詞】 [the opposite は 【不可算名詞】]
(正)反対のもの[人,事,語] 〔of〕.
用例
He thought quite the opposite. 彼は正反対に考えた.
http://ejje.weblio.jp/content/opposite
if notはイディオムになってるけど、あえて省略されてるとこを書き出すと、
if it is not completely
itはこの例文だとThe sacrificesになる。
if not のifは、「~ではなかったとしても」っていう逆接の意味が含まれてるんだろう。
追記;