〜に至って|〜にいたって

'Only when things reached the point of X (did ...)': marks an extreme or critical stage that is finally reached, after which a belated action or realization occurs. Often implies it should have happened sooner.

A formal, written expression used in news reports, essays and critical commentary, typically about governments, organizations or people who respond only after a situation becomes grave. The main clause usually contains ようやく, やっと or 初めて, giving a tone of 'too late' or 'at long last'. Compared with に至っては, which singles out an extreme example, に至って marks the moment a turning point is reached.

• に至ってはN1「に至っては」attaches only to nouns: after describing the general situation of a category, it picks out the most extreme example to comment on, meaning 'as for..., even more so'. 「に至って」instead means 'only after things have reached this point...', so the two cannot be interchanged.
• に至る / に至ったN1「に至る/に至った」is used at the end of a sentence or to modify a noun, stating the result or conclusion finally reached, and can also express arriving at a place. 「に至って」must be followed by a clause meaning 'only at this point did...', with the nuance of being too late, so the two are not directly interchangeable.
• に至ってもN1「に至っても」is a concessive expression meaning 'even at an extreme point or critical juncture, ... still...', with an unchanged state in the following clause, often tinged with dissatisfaction. With 「に至って」, the following clause is a change that finally occurs, so the two are opposite in meaning and cannot be interchanged.
• に至るまでN1「に至るまで」is about scope, stressing that even minor or extreme items are included; it also forms 「AからBに至るまで」, and the following clause is a comprehensive statement. 「に至って」instead marks a temporal turning point — a situation reaching a certain stage before something happens — so the two cannot be interchanged.
• ともなると / ともなればN1「ともなると」means that once someone reaches a special status or stage, the corresponding situation naturally follows, in a neutral register. 「に至って」says that only after a situation has worsened to the extreme does a belated action or realization appear, often with 「ようやく」, and is written language, so the two cannot be interchanged.
• にしてN1「にして」is close in the sense of 'only at... did...', but it attaches only to nouns, typically ages or stages, and lacks any nuance of a situation worsening or of being too late. It can also mean 'at the mere age of...', 'in an instant', or 'both... and...'.

に至って marks the critical point after which something finally happens. に至っては singles out an extreme example ('as for X, even'), に至る / に至った ends a sentence stating an outcome, に至っても means 'even having reached that point, still not', and に至るまで marks the far end of a range ('down to, even'). ともなると / ともなれば describes what is naturally expected at a certain level or status, and にして stresses that only a particular level or stage makes something possible.