U.S. transportation officials told wireless carriers it would not seek any further details in deployment of 5G wireless service beyond Jan. 19 absent any "unforeseen aviation safety issues," according to a previously unreported letter.

U.S. Transportation Secretary Pete Buttigieg and Federal Aviation Administration chief Steve Dickson said in a joint letter AT&T and Verizon Communications agreement to delay C-Band wireless deployment by two weeks "will give us additional time and space to reduce the impacts to commercial flights."

The attached "final term sheet" said unless "unforeseen aviation safety issues" arise the agencies "will not seek or demand any further delays of C-Band deployment, in whole or in part, including a delay of return to routine operations."