Talk about a “live exercise”

Imagine you’re holding an exercise for an anticipated, potential emergency event. Imagine if the emergency event happens during your exercise, albeit to a far lesser degree than what you’re holding the exercise for:

[The] simulation began just hours after a real U.S. Border Patrol mission picked up more than 40 Spanish-speaking migrants who happened to arrive Thursday morning along Miami-Dade beaches. Arrivals like those occur frequently in South Florida, the majority of them from Cuba.