The Pentagon has for weeks now vocally articulated its case for the FCC to rescind a recent approval for Ligado to repurpose spectrum adjacent to that used for GPS, and urged lawmakers to support the department’s side during a highly technical May 6 hearing before the Senate Armed Services Committee.

But while many SASC committee members side with the Defense Department on the matter – as do many of their colleagues in the House Armed Services Committee – several members are requesting more information, and are unsure whether interference from Congress is the right step forward.

Pentagon officials Chief of Space Operations Gen. John “Jay” Raymond, DoD Chief Information Officer Dana Deasy and Undersecretary of Defense for Research and Engineering Mike Griffin testified at the Wednesday SASC hearing, along with retired Coast Guard Adm. Thad Allen, who has spent years working in the radio frequency arena.

Ligado and the FCC were not invited to testify, as SASC leadership noted the hearing would focus on the potential national security risk to GPS, and that the FCC usually falls under the jurisdiction of the Senate Committee on Commerce, Science and Transportation. The Virginia-based company submitted a five-page written testimony to the committee ahead of the hearing to state its case and lament the fact that company officials were not invited to speak before lawmakers.

SASC Chairman Jim Inhofe (R-Okla.) and Ranking Member Jack Reed (D-R.I.) had previously made their alliance to the Pentagon known in an April 23 op-ed published in Defense News, joined by their HASC counterparts. Many SASC members also sided with the Defense Department’s perspective that Ligado’s plan could cause dangerous interference for U.S. GPS receivers, and that company-funded studies that suggested the risk could be mitigated were in fact insufficient.

However, several lawmakers said they wanted to see additional documentation and hear from the FCC and other government agencies before making an assessment. Sens. Angus King (I-Maine), Tom Cotton (R-Ark.) and Tim Kaine (D-Va.) each brought up the fact that Attorney General William Barr and Secretary of State Mike Pompeo have issued statements of support for the Ligado proposal.

“What do you see that Attorney General Barr and Secretary Pompeo don’t see?” Cotton asked those testifying. Deasy told the lawmakers he could not speculate on what those individuals assessed, but that “as a technologist for almost 40 years now, I see the science” as well as the studies that, to the Pentagon, prove that Ligado’s proposal would negatively impact millions of GPS civilian and military receivers across the country.

Deasy told reporters in a Wednesday evening teleconference that the Pentagon found some “real fallacies and problems” with Ligado’s studies on the topic, mainly that researchers tested a small number of receivers in a short period of time, and did not take contributing factors into account when testing the power levels of the receivers.

“We just have a different opinion on the methodology,” he said.

The Pentagon is now going through the process of working to get the FCC’s approval reversed, Deasy continued. One avenue could be legislative action, though he noted that the specific format it would take was not yet clear. The department has until May 29 to file for reconsideration with the FCC, officials said Wednesday.

“What we’re doing right now is we’re spending a lot of time looking through that order and specifically identifying the areas and the reasons why we believe reconsideration is necessary,” Deasy added.

Some SASC lawmakers were unclear on what the next move would be on their end, with members including Sens. Jeanne Shaheen (D-N.H.) asking what it was the Pentagon was asking Congress to do, and Kaine asserting that without testimony from the FCC and Ligado, it was difficult for lawmakers to take sides.

It remains unclear how Congress will move ahead with the dispute. SASC Member Roger Wicker (R-Miss.) chairs the Senate Commerce, Science and Transportation Committee and at the hearing Inhofe expressed the hope that Wicker’s committee would schedule a hearing for the FCC and Ligado side. Requests for comment from the committee were not answered by Defense Daily’s press time Friday.

On Thursday, a bipartisan group making up nearly half of the House Armed Services Committee sent a letter to the FCC commissioners requesting a series of document copies and answers to questions within seven days of the letter being sent.

“We are concerned that your approval of any mitigation efforts not rigorously tested and approved by national security technical experts may be inconsistent with the legislative direction to resolve concerns prior to permitting commercial terrestrial operations,” the lawmakers said. “We urge the commission to reconsider and impose additional mitigation steps to address the concerns of these users.”

The signatories included 13 Democrats and nine Republicans, among them HASC Chairman Adam Smith (D-Wash.) and Ranking Member Mac Thornberry (R-Texas). Although the House returns to Capitol Hill May 12 after over one month on recess, HASC has not yet scheduled any hearings.

Many industry partners with an interest in GPS issued letters of support for the Pentagon’s spectrum policy and warning of the impact of the FCC’s decision on national security. The letters were from trade associations including the National Defense Industrial Association, Aerospace Industries Association and the Transportation Construction Coalition, and a general industry letter signed by 68 organizations including airlines, defense contractors, and mail and cargo carriers, among other companies.