The threats targeted Southwest Airlines Flight 2492, which arrived at Atlanta from Milwaukee, and Delta Air Lines Flight 1156, which arrived from Portland, Oregon, said Reese McCranie, a spokesman for Hartsfield-Jackson Atlanta International Airport. Both planes landed safely.
The passengers were taken off the aircraft, and police bomb and K-9 teams examined both planes, authorities said.
The threats were posted on the social media network Twitter, said Preston Schlachter, a spokesman for the North American Aerospace Defense Command. After being alerted, military officials sent two F-16 fighter jets from a base in South Carolina to escort the commercial aircraft to Atlanta.
Upon landing, the Southwest Airlines flight taxied to a remote area where the passengers and the aircraft were rescreened, company officials said in a statement.
"Our top priority is the safety of our customers and employees," Southwest officials said. "We cannot comment on the nature of the security situation."