At the end of the day, alarm was raised due to the threat of ballistics

On the evening of the 17th, the alarm was raised in the Kharkiv, Dnipropetrovsk, Donetsk and Zaporizhzhya regions.

Dzherelo: Power in Telegram 

Verbatim: “There is a threat of stagnation of ballistic armor in areas where the alarm has been sounded! Do not ignore the alarm signals!”