US Transportation Secretary Sean Duffy:
Activity returns to normal after the cessation of air traffic.
American airspace has become safe to fly.
Some flights continue to be delayed or canceled.
The reason for the communication failure is still unclear.
We use old devices in air traffic control systems.
Malfunctions occurred during maintenance work.
We were not subjected to a cyber attack yesterday.
The grounding of air traffic was not the result of a cyber attack.
Congress did not understand the importance of "navigational devices".
We support airlines to "restore flights".