DENVER — NORAD is considering removing two of its 18 Air Force sites from 24-hour alert, saying it would save millions of dollars without compromising its ability to defend against 9/11-style attacks.

A Government Accountability Office report released Thursday said the North American Aerospace Defense Command might take fighter jets in Duluth and at Joint Base Langley-Eustis, Va., off 24-hour alert.

No decision has been made and both sites remain on alert, said Navy Capt. Jeff Davis, a NORAD spokesman.

NORAD, based at Peterson Air Force Base, Colo., told the GAO the move wouldn’t hurt its ability to scramble fighters to intercept hostile or hijacked aircraft. NORAD said it used analyses by computer modeling, a panel of experts and other methods to arrive at that conclusion.

The Air Force told the GAO the move would save $73.1 million over five years. The proposal appeared to be unrelated to mandatory budget cuts taking effect Friday.

Units that would be taken off around-the-clock alert are the Minnesota Air National Guard’s 148th Fighter Group in Duluth and the Vermont Air National Guard’s 158th Fighter Group, which flies NORAD missions out of Langley-Eustis.

It wasn’t known how other operations at the two fighter groups would be affected. The GAO said most of the savings would come from shifting full-time personnel to part-time status.

The Minnesota National Guard issued a statement saying only that it was aware of the report and that the fighter wing remained on alert.

A spokesman for the Vermont National Guard did not immediately return a call.

An earlier GAO report said the other NORAD alert sites are in Alaska, Arizona, California (two), Colorado, Florida, Hawaii, Louisiana, Maryland, Massachusetts, New Jersey, Ohio, Oregon, South Carolina, Texas and Wisconsin.

NORAD is a joint U.S.-Canada command responsible for protecting the skies over both nations and monitoring sea approaches.