は～となっているIt is (has been), Have/has become, Happen to be, Has been established

(A) は (B) となっている is a common expression used to show that '(A) is becoming (B)', or (more commonly) '(A) has become (B)'. This expression will only appear with nouns, or な-Adjectives in their 語幹(ごかん) (stem form). (A) は (B) となっている is often translated as '(A) happens to be (B)', '(A) has been established as (B)', or 'it has been decided that (A) is (B)'.

Let's have a look at some examples, and then how this structure is formed.

Despite the different translations, (A) は (B) となっている always has the same meaning, which can be understood as follows:

(A) は - (A) is a constant unchanging thing.

(B) と - (B) is a result. (coming from the case marking particle と's role in highlighting results.)

なっている - (A) is existing in the state 'having arrived at the result of (B)'.

Due to this, the literal translation may be thought of as 'it is now that (A) is (B)' in almost all situations.

Caution

(A) は (B) となっている may be rephrased to (A) は (B) になっている. However, に will remove much of the feeling of a 'result', or 'finality'. Due to this, it will just sound like (A) is becoming (B), but is not necessarily that way yet.

Caution

In writing, おる is not always considered a 'formal' equivalent of いる, especially in set phrases. となっている is often seen as となっており, instead of となっていて. This is particularly common in news articles.