Just weeks before the alleged London terror plot broke, some U.S. airports had been discussing massive expansion of the retail around airports.

In what would be the first project of its kind in the U.S., Dallas/Ft. Worth International is in the planning stages for a 600-acre mixed-use development that would include up to 800,000 square feet of retail space. And Denver International has already awarded a development contract for a 17-acre site to build a mixed-use complex.

“They are looking to not be so dependent on what airlines can pay,” says Bruce F. Katz, founder and president of San Francisco-based consulting firm Retail Focus. The new projects, he says, are just the most ambitious extension of a move to develop non-airline revenue that has been under way for 15 years.

In the case of Dallas/Ft. Worth, the airport is attempting to develop a vacant property on its southern tip tentatively called Passport Park. The airport's management is hoping to bring in stores like Target, Wal-Mart and PetSmart. Meanwhile, Redwood Real Estate Partners and CMCB Development Co. have been chosen by Denver International to develop a 17-acre land parcel about a mile away from the airport's main terminal into 60,000 square feet of retail. It could eventually grow to 500 acres.