に至って

に至って is used to indicate that a certain realization, change, or action occurs only after reaching a particular stage or situation.

It emphasizes that before this point, the situation did not change, and only now, after things have developed or progressed, has something finally happened. The grammar often carries a nuance of lateness, seriousness, or inevitability.

This expression is mainly used in written or formal Japanese, such as news articles, reports, and serious explanations.