A recent uptick in sightings of unidentified flying objects — or as the military calls them, “unexplained aerial phenomena” — prompted the Navy to draft formal procedures for pilots to document encounters, a corrective measure that former officials say is long overdue.

As first reported by POLITICO, these intrusions have been happening on a regular basis since 2014. Recently, unidentified aircraft have entered military-designated airspace as often as multiple times per month, Joseph Gradisher, spokesman for office of the deputy chief of naval operations for information warfare, told The Washington Post on Wednesday.

Citing safety and security concerns, Gradisher vowed to “investigate each and every report.”

He said, “We want to get to the bottom of this. We need to determine who’s doing it, where it’s coming from and what their intent is. We need to try to find ways to prevent it from happening again.”