The military is conducting an air defense exercise this week around the nation's capital that includes launching jet fighters and deploying surface-to-air missile launchers, military officials said Monday.
The exercise, which coincides with the anniversary of last year's terror attacks, is to test the military's ability to respond to an attack from the air, said Lt. Col. Mike Halbig, a Pentagon spokesman. He would not describe the simulated threat further.
At the Pentagon, the military deployed an Avenger, a Humvee armed with heat-seeking Stinger missiles. It was unclear whether other SAM systems, such as the long-range Patriot, also were involved.
The ground systems are not carrying functional missiles, Halbig said. The exercise, called "Clear Skies II," is run by NORAD, the North American Aerospace Defense Command, and will involve about 300 people. Jet interceptors and other aircraft also will take part.
It has been planned for several months, officials said.
However, Gordon Johndroe, a spokesman for the White House Office of Homeland Security, said the exercise is routine and not the result of any threats, but he said "it is not unhelpful" that the exercise was under way at a time of high alert for the nation.
On Friday, armed military jets resumed round-the-clock patrols over New York and Washington. Pentagon officials would not say Friday whether the air patrols were resumed because of a specific threat or because of the anniversary of the attacks.
The Defense Department started the patrols after the Sept. 11 attacks and began phasing them out in April, Pentagon officials have said. The patrols had continued sporadically when officials received threats.