It's only a drill, Chicago.
Reports of black military helicopters circling the Willis Tower and flying over Lake Michigan Monday night lit up local social media with theories and speculation.
Some thought it was part of "Transformers 4," which begins filming in Chicago Aug. 18 through Sept. 27. Others wondered if it was a precaution for President Obama's visit to Illinois on Wednesday.
Anyone else seeing 3 black helicopters fly low around the loop with no lights on? #chicago What is going on?
— Aniz Ruda (@anizruda) July 23, 2013
— Andrew Steele (@Steele36) July 23, 2013
The real reason? Chicago is hosting routine military, low-range helicopter training exercises through Thursday, according to the Office of Emergency Management and Communications.
Cities across the nation are performing similar training exercises to ensure the military knows the proper protocol in urban areas, the OEMC said. Military service personnel are going through mandatory training to prepare for future overseas deployments.
Similar exercises were performed last year in Chicago.
Training exercises are not open to the public and are designed to limit the disruption of Chicago residents.