Zumwalt-class destroyers may receive SPY-6 radars from frigates - Naval News
Retrofitting Failure: The Zumwalt-Class and the $32 Billion Learning Curve
The U.S. Navy is evaluating a proposal to retrofit AN/SPY-6 radar systems—originally manufactured for the cancelled Constellation-class frigate program—onto all three operational Zumwalt-class destroyers as part of the Zumwalt Enterprise Upgrade Solution (ZEUS). Raytheon has received Navy funding to develop combat management system modifications enabling SPY-6 integration, while both contractors and Navy officials have expressed confidence in the technical feasibility. The SPY-6(V)3 variant, dimensionally comparable to the incumbent AN/SPY-3, could be installed without major structural modifications; however, no final decision has yet been made. The backfit represents one element of a broader strategic pivot to transform the Zumwalts from their failed original concept as gun-armed littoral platforms into long-range hypersonic strike assets aligned with the wider Aegis fleet.
The Zumwalt Class in Transition
The Zumwalt-class destroyers represent one of the U.S. Navy's most dramatic strategic reversals. Originally envisioned as a 32-ship class optimized for naval surface fire support (NSFS) in shallow-water operations, the platform's distinctive tumblehome hull and composite deckhouse were engineered to achieve radar cross-section comparable to that of a fishing boat—approximately fifty times more difficult to detect than a conventional destroyer.1 However, rising costs for the Long-Range Land-Attack Projectile (LRLAP) ammunition essential to the ship's core mission rendered the 155-millimeter Advanced Gun System economically unsustainable, and procurement was cancelled well before the first ship's commissioning.
With only three ships authorized and built—USS Zumwalt (DDG-1000), USS Lyndon B. Johnson (DDG-1002), and USS Michael Monsoor (DDG-1001)—the Navy has radically reoriented the class toward extended-range strike warfare. Beginning in 2023, both AGS turrets were removed from each destroyer and replaced with vertical launch system (VLS) cells accommodating the Conventional Prompt Strike (CPS) hypersonic missile system.2 USS Zumwalt completed this conversion in late 2025, and now carries twelve CPS missiles in four Advanced Payload Modules forward of the superstructure.3 USS Lyndon B. Johnson is undergoing similar modifications at Ingalls Shipbuilding in Pascagoula, while USS Michael Monsoor is scheduled for conversion during its next maintenance availability.
The CPS missile, jointly developed by the Army and Navy, achieves Mach 5+ velocity and delivers a Common Hypersonic Glide Body (C-HGB) across ranges exceeding 1,725 nautical miles—a dramatic capability expansion compared to the AGS's notional 63-nautical-mile range.4,5 This transformation has effectively shifted the Zumwalt-class from a littoral gun platform to a strategic-depth strike destroyer, fundamentally altering the operational calculus for the ships' remaining service life.
The Combat System Modernization: ZEUS
Recognizing that hypersonic strike capability alone would not suffice for twenty-first-century fleet operations, the Navy initiated the Zumwalt Enterprise Upgrade Solution (ZEUS)—a comprehensive combat system modernization program first formally outlined in a Request for Information (RFI) issued in November 2022.6 ZEUS encompasses far more than radar replacement alone. The program includes integration of the Surface Electronic Warfare Improvement Program (SEWIP), the undersea warfare combat system SQQ-89, and the Cooperative Engagement Capability (CEC) datalink—measures designed to align the Zumwalt-class more closely with the Aegis-equipped fleet standard and enhance network-centric warfare integration.7,8
The radar upgrade component reflects a critical shortcoming in the original Zumwalt design. The AN/SPY-3 multifunction radar, while performing well in its X-band search and track role, was never intended to shoulder the full burden of air defense alone. Zumwalt-class destroyers were originally equipped with a dual-band radar architecture pairing the SPY-3 with the AN/SPY-4 S-band volume search radar. However, in June 2010, Pentagon acquisition officials elected to delete the SPY-4 as a cost-reduction measure, requiring the SPY-3 to be reprogrammed to perform both horizon search and volume search functions simultaneously—a compromise that limits its capability to manage large-scale air attacks while providing fire control for multiple simultaneous engagements.9,10 The SPY-3 also lacks integration with modern ballistic missile defense systems, a growing liability as the Navy faces advanced cruise-missile and hypersonic threats.
The AN/SPY-6: A Generation Forward
The AN/SPY-6 represents the latest generation of Raytheon naval radar technology. First delivered to the Navy in July 2020, the SPY-6 is built on a modular, scalable architecture employing Radar Modular Assemblies (RMAs)—self-contained radar modules, each approximately two feet per side, that function as individual transmit/receive elements.11 This modular approach enables the Navy to field multiple variants optimized for specific platforms and mission sets, ranging from the full four-sided SPY-6(V)1 system aboard Flight III Arleigh Burke-class destroyers (with 37 RMAs per face) to more compact configurations for smaller combatants.
The SPY-6(V)3 configuration under consideration for Zumwalt-class integration employs a three-sided phased array, each with nine RMAs, providing volume search and track capabilities across extended detection ranges and advanced electronic scanning performance characteristic of modern AESA radar systems.11,12 The SPY-6(V)3 is already planned for installation on Constellation-class frigates (for ships remaining under construction) and serves as the primary air and missile defense radar aboard Gerald R. Ford-class aircraft carriers beginning with USS John F. Kennedy (CVN-79).11 This commonality across platform classes has significant implications for fleet logistics, training, and maintenance.
The SPY-6 system offers approximately 15 decibels improved sensitivity compared to the SPY-1 radar architecture that equips the Aegis fleet—equivalent to detecting targets half the size at twice the distance—and provides simultaneous defense against ballistic missiles, cruise missiles, air and surface threats, plus organic electronic warfare capability.11 Integration with CEC enables true network-centric air defense, where each ship's SPY-6 radar data is fused with information from surrounding platforms to create a composite battlespace picture far superior to what any single ship could achieve in isolation.
The Constellation-Class Cancellation: An Unexpected Opportunity
The Constellation-class frigate program, awarded to Fincantieri Marinette Marine in April 2020, was conceived as a more affordable complement to the DDG-51 Arleigh Burke-class destroyer. The design was based on a scaled adaptation of Marinette's FREMM (Frigate European Multi-Mission) platform, itself a derivative of the Italian FREMM design with extensive Americanization to meet Navy survivability and electromagnetic requirements.13,14 However, the program encountered cascading delays. As of April 2024, the lead ship, USS Constellation (FFG-62), was only 10 percent complete, with the Navy's FY2026 budget projecting delivery slipping from the original 2026 target to April 2029—a delay of 36 months at an estimated cost of $1.5 billion.14,15 The Government Accountability Office identified fundamental design stability issues, with the ship becoming significantly heavier than anticipated and achieving far less than the promised cost advantage over the larger, more capable DDG-51.
On 25 November 2025, Secretary of the Navy John C. Phelan cancelled all but the first two ships in the Constellation-class program as part of a comprehensive Navy fleet strategy review.16 At the time of cancellation, the lead frigate was reported 12 percent complete. The Navy elected to complete the two ships under construction (FFG-62 and FFG-63) to preserve Marinette Marine's industrial capacity and maintain continuity of shipyard employment, but halted procurement of the remaining four ships on contract. The Navy subsequently announced a new frigate competition for a smaller, faster-to-build design based on the U.S. Coast Guard's National Security Cutter (NSC) hulform, designated FF(X)—an architecture explicitly not optimized for the SPY-6 radar due to size constraints.16,17
This cancellation decision created a windfall of surplus long-lead-time items manufactured for the Constellation-class program. According to John Tobin, Associate Director for International SPY Radar Programs at Raytheon, SPY-6(V)3 radar arrays originally procured for the cancelled frigates remain in inventory. Raytheon and Navy officials have indicated that these systems could be repurposed and installed on the Zumwalt-class at considerably lower total cost than procuring entirely new radar suites.6 The decision to salvage these components represents pragmatic asset stewardship in an environment of fiscal constraint.
Technical and Programmatic Feasibility
Raytheon officials have expressed confidence in the technical feasibility of the SPY-6 backfit. Jennifer Gauthier, Vice President of Naval Systems & Sustainment at Raytheon, stated in an interview conducted in Tokyo in May 2026 that "we are currently in discussions with the U.S. Navy and nothing has been decided," while elaborating on Raytheon's ongoing development efforts. Importantly, she confirmed that Raytheon had received Navy funding for development work on the Zumwalt combat management system specifically intended to enable SPY-6 integration, and that the company had established "the first certified, classified software factory for Zumwalt" enabling rapid, secure software uploads to the ships without the extended procurement and testing cycles traditionally required for fleet updates.6
From a physical integration perspective, the SPY-6(V)3 is dimensionally comparable to the incumbent SPY-3. Tobin noted that the SPY-3 is "roughly comparable in size" to the SPY-6(V)3 configuration of nine RMAs, suggesting that physical installation would not require substantial deckhouse modifications or structural rework.6 This point is significant; the Zumwalt-class composite deckhouse is one of the ship's most complex and costly structural elements, and any extensive modification would substantially increase backfit cost and risk schedule slippage.
The Navy has signaled its commitment to the modernization path through concrete funding actions. On 20 April 2026, the Navy awarded Raytheon a $213.4 million contract modification for continuation of Zumwalt-class combat system integration, modernization, installation, testing, and sustainment through 2027.8 This funding supports development activities intended to prepare the ships for future upgrades and demonstrates sustained naval commitment to keeping the Zumwalts at an acceptable combat readiness level throughout their operational lifespans.
Strategic and Doctrinal Implications
The SPY-6 backfit should not be viewed in isolation, but rather as a single element in a comprehensive effort to transform the Zumwalt-class from an aberrant platform pursuing a failed operational concept into an integrated member of the twenty-first-century fleet. The combination of hypersonic strike capability (via CPS), improved air and missile defense (via SPY-6), undersea warfare integration (via SQQ-89), modern electronic warfare systems (via SEWIP), and network-centric capability (via CEC) would position the Zumwalt-class as a formidable multi-mission platform capable of fulfilling strike, air defense, and information-warfare roles across the operational spectrum.
The three Zumwalt-class destroyers are expected to remain in service for decades. Without modernization, they would become increasingly obsolete, representing a diminishing return on the $32 billion invested in the class's research, development, and construction. The ZEUS program, including the SPY-6 backfit, represents the most cost-effective path to preserving their relevance and utility within the constrained fiscal environment the Navy now inhabits.
Critically, the SPY-6 backfit would enhance the Navy's ability to operate in contested environments. The improved detection range, ballistic missile defense capability, and network-centric integration afforded by the SPY-6 would significantly increase the Zumwalts' survivability in scenarios involving near-peer competitors equipped with advanced antiship cruise missiles and ballistic-missile threats. In the context of potential Pacific operations against peer adversaries, every incremental improvement in sensor capability and defensive integration carries strategic weight.
Remaining Uncertainties and Next Steps
No final decision has yet been made regarding the SPY-6 backfit. Navy officials and Raytheon representatives alike characterize the current phase as one of active dialogue and development work, with no commitment to proceed. Several factors will likely influence the Navy's ultimate decision: the outcome of ongoing ZEUS integration testing and combat management system development; the final cost estimate for the backfit across three ships; schedule implications relative to other competing modernization priorities; and the availability of repurposed SPY-6(V)3 arrays from the cancelled Constellation-class program as the Navy completes those two remaining frigates and assesses its actual surplus inventory.
The Congressional Research Service and Government Accountability Office will likely scrutinize any decision to proceed, particularly given Congress's longstanding concerns over Zumwalt-class cost overruns and program management. The Navy will need to make a compelling case that the SPY-6 backfit represents a prudent investment in fleet readiness rather than merely throwing additional resources at a historically troubled program.
The most likely scenario involves a phased approach, with USS Zumwalt receiving the initial SPY-6 installation during a future deployment to sea availability, followed by USS Lyndon B. Johnson and USS Michael Monsoor in subsequent modernization periods. This approach would allow the Navy to validate integration, test operational employment, and refine procedural and training requirements while preserving the ability to adjust subsequent installations based on lessons learned.
Conclusion
The potential backfit of AN/SPY-6 radar systems to the Zumwalt-class destroyers represents a pragmatic response to both technical shortcomings in the original design and fiscal realities that preclude procuring entirely new sensor suites. By leveraging surplus systems from a cancelled competitor program, the Navy can modernize three aging platforms at a fraction of the cost of new-build radar integration. The technical feasibility appears sound, contractor development efforts are well underway with Navy financial support, and senior Navy officials have expressed optimism regarding the modernization path.
What began as a technology-demonstrator for naval gun fire support has been progressively transformed—first into a littoral surface fire support platform, then into a hypersonic strike destroyer, and now potentially into a network-integrated multi-mission combatant capable of holding its own within the modern fleet. The SPY-6 backfit, if approved and executed successfully, would represent the final critical piece of that transformation, converting the troubled Zumwalt-class from a symbol of failed innovation into a capable platform suited to contemporary naval warfare. Whether the Navy ultimately commits to the backfit will reveal much about the service's willingness to invest in the long-term modernization of existing platforms rather than perpetually pursuing new starts.
A Final Irony
The arc of the Zumwalt-class offers a cautionary lesson in defense acquisition. The original concept—a gun-armed littoral strike platform with stealth features—was sound in theory but ultimately unsustainable: the Long-Range Land-Attack Projectile proved economically ruinous, the gun-centric mission concept lost political support, and only three ships were ever built instead of the planned 32. What the Navy is now contemplating—a long-range hypersonic strike destroyer with SPY-6 air defense and network integration—bears almost no resemblance to what was originally approved. Yet after fifteen years and more than $32 billion in sunk costs, after multiple complete mission redesigns, and after stripping out systems and bolting on others, the Zumwalts may finally achieve utility as capable twenty-first-century surface combatants. The tragic irony is that three Flight III Arleigh Burke-class destroyers, equipped with SPY-6 and conventional strike missiles from their inception, would have cost considerably less and delivered equivalent or superior capability a decade earlier. The Navy has, in effect, paid dearly for a protracted learning experience conducted aboard billion-dollar warships. If the SPY-6 backfit proceeds and succeeds, the Zumwalts will vindicate themselves not through faithfulness to their original design concept, but through the Navy's willingness to change course fundamentally and repeatedly until three troubled platforms finally become genuinely useful assets. That is a hard-won but valuable lesson for an institution that struggles with admitting error and altering course.
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