Military training flights are scheduled this week over the Washington area to test air defense response.
The North American Aerospace Defense Command (NORAD) says the flights are scheduled early Wednesday. Civil Air Patrol aircraft and a Coast Guard helicopter are to take part in the exercise along with Air Force F-16 fighter jets.
NORAD says the flights are scheduled to take place between 3 a.m. and 5 a.m. and are designed to test intercept and identification operations.
The exercises have been conducted throughout the U.S. and Canada since the terrorist attacks on Sept. 11, 2001.