By the time fans learned that Taylor Swift ‘s three-night run in Vienna would be canceled due to a terror threat , authorities had already been working tirelessly behind the scenes to uncover and foil a plot that threatened the lives of thousands of people. The week’s events have rekindled concerns internationally about large-scale event safety, with Swift’s concerts the largest to face such a threat in years. Multiple experts in live event security and risk management tell Rolling Stone that canceling the concerts was the correct decision, even though the police intervened before the attack could take place.

Neither Swift nor promoter Barracuda Music were legally compelled to stop it, but the decision, the experts say, comes down to common sense . “There was a credible terrorist threat, related to ISIS. The guy who was arrested had the means of committing mass carnage,” Steve Adelman, an attorney who serves as vice president of the Event Safety Alliance, tells Rolling Stone .

“That’s more than enough to warrant a cancellation.” Mark Camillo is senior advisor for Contemporary Services Corporation, which provides security and crowd management expertise for sports and entertainment events in the U.S.

“From all that I’ve read, and looking at security information and unclassified intelligence briefings, it appears that the promoters made the decision out of an abundance of caution and that authorities didn’t know how far-reaching this was, so I think they ma.