Bush will re-open Washington airport after safety measures in place.(Chicago Tribune)

WASHINGTON_President Bush is prepared to reopen Ronald Reagan National Airport in Washington, the only major airport still closed after the Sept. 11 terrorist attacks, but only after safety measures are in place at the airport and aboard the jetliners that use it, his aides said Monday.

Bush also declared that the administration is making slow but steady progress in tracking the terrorists responsible for the Sept. 11 attacks, and he again urged Americans to be patient as the U.S. prepares to retaliate against known terrorist networks.

Bush aides cautioned that the president had not signed off on a final plan for Reagan National and said it would take some time before the newly remodeled airport could reopen.

Among the security changes Bush seeks is the placement of air marshals on incoming and outgoing flights to the airport, which is just across the Potomac River in Virginia. The president also is considering limiting the number of flights in and out of the airport.

The Federal Aviation Administration would have to approve such changes.

White House spokesman Ari Fleischer said Bush weighed the serious concerns raised by the Secret Service and others given the airport's proximity to the Capitol, the White House and other government buildings and landmarks.

Bush also took into consideration the considerable cost to industry, individual jobs and tourism entailed in shuttering the airport. The airport is the hub for U.S. Airways, and the airline's executives said the company could be doomed by the closing of Reagan National.