WASHINGTON — The Pentagon has denied the Joint Surveillance Target Attack Radar System recapitalization program approval to move into the next phase of the acquisition cycle, another setback for a long-delayed effort to replace the Air Force's ground surveillance fleet.

The Pentagon's Defense Acquisition Board reviewed the JSTARS program during a Sept. 18 meeting that was widely expected to approve a "Milestone A" decision to move into the technology maturation and risk reduction phase. But the Pentagon did not give the green light and instead sent the Air Force and industry partners back to complete additional work on the program.

During a successful Milestone A review, the Pentagon weighs a program's acquisition strategy and decides on the best path forward.

"Overall, the Defense Acquisition Board meeting held on Friday, 18 Sept. went well.  Although a Milestone A decision was not approved at that time, there was good discussion," Air Force spokeswoman Ann Stefanek told Defense News in a Monday email. "We have some action items to accomplish so everyone more clearly understands the program risks and the technical details."

Stefanek declined to specify what additional work needs to be done. Industry representatives declined or were unavailable to comment.

The Air Force officially kicked off the competition to replace its aging E-8 JSTARS in early August, awarding a trio of competitors each a pre-engineering and manufacturing development contract, for a total of $31.4 million. Northrop Grumman, which builds the existing aircraft, is teamed with Gulfstream and its G550 business jet, with L-3 helping with integration. Lockheed Martin is working with Bombardier on a proposal based on the Canadian company's Global 6,000 business jet. Meanwhile, Boeing is offering a modified version of its 737-700 commercial airliner.

Industry widely expected a Milestone A decision, which would authorize additional contract money for system and platform demonstrations, at the end of September, with a downselect for the EMD award in the summer or early fall of 2017. The Air Force had initially planned to declare initial operational capability for JSTARS in fiscal 2022, but the latest budget proposal delayed that date to fiscal 2023.

Recently, Air Force leadership has touted an effort to speed up delivery of weapons to troops through a more transparent acquisition process, an initiative called "should schedule." William LaPlante, assistant secretary of the Air Force for acquisition, said earlier this month that the service wants to leverage this effort to accelerate the JSTARS timeline.

"I would love to be able to pull, to challenge, for example, on a program like JSTARS recap, hey, let's pull that thing to the left, let's see if we can get that IOC as left as possible," LaPlante told reporters during a roundtable at the Air Force Association's annual air and space exposition. "Let's start challenging ourselves in the next year to start flowing down the requirements and then put the right schedule together. My bias is we move that thing, we make it as short as we can."

However, LaPlante warned in July during an event hosted by the Center for Strategic and International Studies in Washington that budget uncertainty and sequestration could hamper the Air Force's ability to move ahead on JSTARS.

It is unclear how much of an impact the Pentagon's decision to deny Milestone A approval will have on program development. While several analysts contacted by Defense News said such a decision is abnormal, the industry teams can still move ahead with the existing contracts.

One potential problem is that industry has several divergent approaches to recapitalizing the JSTARS fleet, according to Teal Group analyst Richard Aboulafia postulated. Boeing is looking at a much larger, commercial-based derivative for the new JSTARS, while Northrop has proposed a smaller, business jet solution.

"It might be the service itself and its definition of what it wants," Aboulafia said. "It's one thing when you look at competitors that are pursuing a very similar idea ... with JSTARS they are very different approaches [and] it might take some time before they get comfortable with how they are going to mature these systems and operate them."

Another problem is the Air Force's plan to fund the program, Aboulafia said. The service is planning to funnel operations and maintenance (O&M) savings from retiring the current JSTARS fleet into procuring a new aircraft. However, it is not always easy to reprogram O&M funding into the procurement account.

Current budget uncertainty, and the possibility the Pentagon may be forced to operate under a yearlong continuing resolution, also complicates the situation.

One analyst and defense industry consultant, Loren Thompson, offered another possible reason for the holdup: Certain Pentagon officials are pushing for an unmanned aircraft to replace the current JSTARS fleet.

"The problem here is partly due to resistance from drone advocates in OSD," Thompson said. "I think we will get to a formal Milestone A decision when the cost estimators in the Air Force and the drone proponents in OSD are either satisfied or contained."

Twitter: @laraseligman