"The Transport Layer for Tranche 3 is not funded," a Space Force official said, adding that "those requirements are going to be rolled into the requirements being filled by the SDN backbone." With that terse declaration at a Pentagon briefing, the Space Force signaled a concrete break from the Space Development Agency’s Transport Layer approach and a renewed push to build a new Space Data Network (SDN) backbone.
Transport Layer Tranche 3: funding pulled, Congress history remembered
The Space Force told reporters that it will not fund further iterations of the Transport Layer constellation managed by the Space Development Agency (SDA). The Transport Layer concept had envisioned successive tranches of low-earth-orbit relay satellites. The service previously tried to zero out funding for SDA’s Tranche 3, but Congress restored $500 million to that effort in the prior fiscal cycle. The latest decision is to stop future Transport Layer funding and absorb those requirements into the SDN backbone.
SDN backbone: $1.6 billion reconciliation request and procurement line
Maj. Gen. Frank Verdugo, the Air Force’s deputy assistant secretary for budget, confirmed the Space Force is requesting $1.6 billion in reconciliation funds to build out a proliferated low-earth-orbit SDN backbone — a program he said was "previously MILNET." A Department of the Air Force (DAF) spokesperson told Breaking Defense the effort formerly called MILNET will be funded in a procurement budget line labeled "proliferated LEO SATCOM."
Budget documents released with the FY27 request also show roughly $1.5 billion, drawn from reconciliation, sought for SDN research and development under a dedicated budget line.
What the SDN backbone is meant to do and who will run it
The DAF spokesperson described the SDN program line as a "proliferated LEO mesh constellation and associated ground architecture providing resilient, high-volume, low-latency communications and tactical data links for the Joint Force." Key tasks listed include procuring relay satellites, fielding ground gateways, and onboarding additional vendors into the architecture while using competition and rapid delivery timelines.
The architecture will be overseen by Col. Ryan Frazier, the Space Force’s Space-Based Sensing and Targeting portfolio acquisition executive. The SDN is explicitly tied to operational ambitions such as enabling projects like the Golden Dome missile defense shield.
SDA’s tracking layer and organizational consolidation
While the Transport Layer is being folded into the SDN backbone, SDA remains active in other roles: the agency is launching missile warning satellites as part of a so-called tracking layer. Acting SDA Director Gurpartap "GP" Sandhoo told reporters on April 15 that the agency "probably won't" exist down the road as a portfolio approach absorbs and reorganizes space acquisition efforts. Sandhoo also confirmed the SDN’s scope has expanded to include the transport layer and is slated to become a portfolio executive overseeing missile warning and tracking programs.
Budget context: sweeping increases, program cuts, and personnel growth
The FY27 package accompanying the SDN decision reflects an aggressive expansion of Space Force resources. Officials say the Pentagon is requesting $71.1 billion for the Space Force in FY27, up from $31.6 billion in FY26 — a 124 percent increase in the presented overview. Those totals include reconciliation funds requested alongside the Pentagon’s base budget.
- Buying space systems: +342 percent (compared to enacted FY26)
- Research & development: doubled
- Operations & maintenance: +70 percent
- Military personnel: +29 percent
Officials said the additional funds would support adding 2,800 Guardians with a hiring focus on "space, intelligence, cyber and acquisition career fields," and would benefit missions including space domain awareness and secure SATCOM. Not all programs survived: the day before the budget drop the Space Force killed the long-troubled GPS ground system OCX, and the FY27 request includes no funding for Next-Gen Overhead Persistent Infrared Polar (NGP). The DAF spokesperson said the service is "evaluating the viability" of NGP and "will have an acquisition decision in FY27"; Congress previously restored $436 million to NGP in FY26.
Conclusion: a shift in architecture, questions about platforms remain
The Space Force has reframed how it intends to move high-volume, low-latency data among space sensors and shooters, shifting requirements off SDA’s Transport Layer and into an SDN backbone funded through a proliferated LEO SATCOM procurement line. The service has tied personnel growth, major procurement increases, and R&D funding to that pivot. What remains unsettled from the disclosures is which specific platforms and vendor mix will execute the SDN backbone — a question the briefing acknowledged when it noted the backbone was "previously MILNET" and that it remains unclear what systems may be used. The service also faces program-level decisions in FY27 on NGP and other initiatives as it implements the portfolio approach Sandhoo described.
