Fighter jets controlled by the North American Aerospace Defense Command plan on intercepting planes posing as possible threats over Phoenix.
Tuesday morning's exercises are part of regular tests of NORAD's ability to respond to airborne threats that have been in place since the Sept. 11, 2001 terrorist attacks.
The fighters will be intercepting other aircraft standing in as possible threats between 10 a.m. and noon and people may see or hear them as they fly above the metropolitan Phoenix area. The flights could be delayed or canceled if bad weather develops.
NORAD provides aerospace warning and control for Canada and U.S. and involves both American and Canadian military commanders.
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