(Bloomberg) -- The Defense Department told lawmakers Ligado Networks LLC’s planned mobile network would cause harmful interference to millions of GPS receivers across the U.S., both civilian and military.

“This is a bad deal for America,” Dana Deasy, the department’s chief information officer, told the Senate Armed Services Committee during a hearing Wednesday. “There are too many unknowns and the risks are too great to allow the proposed Ligado system to proceed in light of the operational impact to GPS.”

Ligado, which wasn’t invited to the hearing, said in a letter to the committee its service would operate at low power and wouldn’t interfere with GPS devices using their assigned airwaves. “These airwaves are separate and distinct” from GPS, Doug Smith, Ligado’s president, and its chairman, Ivan Seidenberg, the former chairman of Verizon Communications Inc., said in the letter.

Ligado won approval April 20 from the Federal Communications Commission, with Republican Chairman Ajit Pai calling the move a “step forward for American leadership in 5G and advanced wireless services.” Federal agencies including the Defense Department and Federal Aviation Administration had objected, citing potential interference to faint GPS signals that come from satellites.

Republican Senator James Inhofe, of Oklahoma, chairman of the Armed Services Committee, and other lawmakers have called for the FCC to withdraw its approval and resolve Defense Department concerns, and that Congress might otherwise act.

“I do not think it is a good idea to place at risk the GPS signals that enable our national and economic security for the benefit of one company and its investors,” Inhofe said Wednesday. “Ultimately, the burden of mitigating harmful interference will be placed on the Department of Defense, and American taxpayers will be left footing the bill.”

At the end of February, Ligado hired David Urban, a longtime ally of President Donald Trump who runs the lobbying firm American Continental Group and has been a vocal defender of the president as a CNN political commentator, to work on its behalf. Despite only working for the company for a little more than a month, the company paid American Continental Group $100,000, according to an April 20 disclosure form.

Urban was a member of the West Point class of 1986 along with Esper and is a personal friend. Urban lobbied the White House, the Pentagon and the State Department, according to disclosures.

Secretary of State Michael Pompeo, another member of the class of 1986, on April 16 called approval of Ligado’s plan “vital to our national security.”

Attorney General Bill Barr in an April 16 statement called approval for Ligado “essential if we are to keep our economic and technological leadership and avoid forfeiting it to Communist China.”

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