WASHINGTON — Members of Congress appear divided over the performance of the Army's key battlefield communications capability — the Warfighter Information Network-Tactical — and whether to accelerate or do away with the program.

Army Chief of Staff Gen. Mark Milley told senators Thursday during a Senate Armed Services Committee hearing that he was taking a hard look at the program and the network as a whole to make sure it functioned properly now and could hold up in more contested operations in the future.

Service leaders are "driving a rigorous, thorough and painful review of the entire communication, electromagnetic capabilities of the U.S. Army, of which WIN-T is one part," he said.

Milley had ordered a review and a new Army network strategy earlier this year.

Milley said he’d have a comprehensive report on the network as a whole in four to six weeks in order to help guide Congress as it marked up policy and spending bills.

A group of 178 House lawmakers signed a letter last month sent to Milley to encourage fielding the service’s WIN-T capability faster, proposing a new fielding approach that would fund the procurement of six brigade sets of WIN/T over the next five years.

And Milley said he had also received a similar letter from "several" senators regarding WIN-T’s acceleration.

Despite the letters urging faster procurement of WIN-T, SASC Chairman John McCain, R-Ariz., used his opening remarks during Thursday’s hearing to blast the program specifically while highlighting Army modernization bungles over the years.

"Most recently the committee has learned of the failure of the Warfighter Information Network-Tactical or WIN-T program and I urge my colleagues, if they don’t pay attention to anything I say today, this program has cost the taxpayer over $6 billion and has yet to meet the requirements of warfighters," he said.

And Sen. Tom Cotton, R-Ark., said he had heard "credible reports that WIN-T has ineffective line-of-sight communications, is not survivable, is too fragile to survive in a contested environment and has an electromagnetic signature so loud that it practically would call for enemy artillery on the top of users’ heads."

Milley admitted to hearing similar reports and said, "we have the same concerns. Frankly, my concern is these systems may or may or may not work in the conditions of combat that I envision in the future with this change of character of warfare."

The chief has said many times the future operational environment is going involve having to go up against near-peer threats in contested environments that require small units, operating independently from command, to move almost constantly to avoid defeat.

The first increment of WIN-T fielded can only function — transmitting, voice, video and data — when a unit is stopped. The second increment of WIN-T is supposed to provide an on-the-move networked communications capability.

Milley, who visited Aberdeen Proving Ground, Maryland, to be briefed on a variety of network and communications programs, listed his concerns about WIN-T: "Line of sight, electromagnetic spectrum, the inability to operate on the move, the inability to operate in large, dense, complex, urban areas or complex terrain and there is a whole series of other things and it is fragile and it is vulnerable, adding the Army is "taking a very, very, deep hard and wide look."

Sen. Elizabeth Warren, D-Mass., said during the Thursday hearing that she thought problems with the first increment of WIN-T had been solved in the second version, noting there is "no obvious substitute" for the communications capability should the Army decide to switch gears.

General Dynamics manufactures WIN-T in Warren’s home state of Massachusetts.

She asked Milley whether the system would be obsolete given its current fielding strategy that wouldn't be complete until 2038 — according to the Army’s most recent fielding plan — and why it is taking so long to field.

Milley acknowledged receipt of the letters urging him to accelerate WIN-T, but said, "I’m not going to accelerate it until I’m convinced it will work in combat against enemies of our country that may be coming in the future, that is where we stand now."

On why it’s taking so long to field WIN-T, the chief told Warren, "that is one of my concerns is a system that is not going to get fielded, it’s already been in development for 10 years. A lot of this stuff is already out of date, so the entire acquisition approach especially in information technologies, we need to review that."

The government’s acquisition system isn’t capable of rapidly buying technology that keeps up with the pace of the commercial world, Milley added, "so by the time we even come up with requirements, these systems are already out of date."