The Pentagon is in the midst of a massive upgrade of its Ground-based Midcourse Defense (GMD) system, designed to protect the U.S. against an attack by an ICBM.

The new Next-Generation Interceptor (NGI) would modernize GMD, arming it with an all-up round that can counter more sophisticated ICBMs. In pursuing the new program, the Missile Defense Agency (MDA) will end the planned purchase of 20 current-generation GMD Ground-Based Interceptors (GBI), after already having canceled a key aspect of that system, the Redesigned Kill Vehicle (RKV). While it works on NGI, the MDA also intends to supplement its defense of the U.S. against ICBMs with shorter-range interceptors that provide regional defense.

• No funding requested for 20 previously planned GBIs
• Agency is studying use of Thaad and Aegis systems for homeland defense

The change in course will not be cheap. GMD itself has cost more than $68 billion over its lifetime. In its fiscal 2021 budget request, the MDA is asking for $664 million in fiscal 2021 for NGI and another $4.3 billion through fiscal 2025.It is an amount that will grow over time and that some worry could pull funding from other urgent priorities, as the type and number of missile threats from other countries evolves to include more sophisticated ballistic missiles and hypersonic weaponry.

The MDA is poised to issue a classified request for proposals to sponsor two contractors through a preliminary design review (PDR) of a new interceptor and kill vehicle—the part of the interceptor that defeats an incoming missile while in space. MDA Director Vice Adm. Jon Hill says the agency plans to award contracts by the end of 2020, with the intention of starting testing in the mid-2020s and putting NGIs in silos by 2027, 2028 or beyond.

“Right now we’re funded through PDR, and you know there’s plenty of arguments out there that you [have] got to go all the way to the [critical design review (CDR)]. We’ll have that conversation when the time is right,” says Hill.

The release of the budget solidifies a plan that has been slowly percolating in the background. Last March, Boeing was put on notice after the RKV—a projectile launched by the GBI booster that is tasked with locating and defeating the incoming ICBM in space—did not meet the needs of its CDR. The Government Accountability Office noted problems with the program meeting its cost and schedule goals “with no signs of arresting these trends.”

By August 2019, Mike Griffin, the Pentagon’s top research and engineering official, stopped work on the RKV after the MDA had spent more than $1 billion to develop it, as it was not proving to be reliable. These RKVs were to ride atop the next 20 GBIs, a project overseen and integrated by Boeing, which Congress had approved in 2018 after a spate of North Korean missile tests.

In concert with ending the RKV, Congress rerouted that funding to the NGI, and the MDA conducted a review of options for the interceptor. Coming out of that assessment, budget officials say they will not buy the 20 new GBIs as the military embarks on NGI development. New NGIs are so far being planned to be placed in silos that were to be inhabited by GBIs, according to Hill. “The current intention is for the Next-Generation Interceptors to be able to work with both current and future sensor systems,” says MDA spokesman Mark Wright.

From a security standpoint, existing GBIs will still protect the U.S. from foreign missile threats, says Hill, but he adds that over time their reliability will begin to fall off. While the NGI program works its way through development, the MDA plans to supplement GMD with a layered network of theater-range systems—the Terminal High-Altitude Area Defense System (THAAD) and the Aegis Standard Missile-3 (SM-3) Block 2A—to fill any gaps in defending the U.S. from North Korean missile attacks.

“What this budget really does for us is it starts to say, ‘Let’s take advantage of these regional systems that have been so successful and are very flexible and deployable,’” Hill says.

In 2020, the MDA will test the SM-3 Block 2A missile against an ICBM.

“When we prove that we can take out an ICBM with an Aegis ship or an Aegis Ashore site with an SM-3 Block 2A, then you want to ramp up the evolution of the threat on the target side, right? We’ll want to go against more complex threats,” Hill says.

That will require upgrading the combat system used by Aegis ships so it can process data from new sensors and engage with a missile. Adding the ability to launch SM-3 Block 2A missiles on ships or from Aegis Ashore sites will give combatant commanders the additional flexibility they have sought, he adds. A future commander could then choose to launch a GBI, THAAD, SM-3 or, when it is ready, NGI.

Such an interim solution using regional systems is still far from a reality.

The Pentagon is requesting $139 million in its fiscal 2021 budget to “initiate the development and demonstration of a new interceptor prototype to support contiguous U.S. defense as part of the tiered homeland defense effort,” the MDA’s budget materials state. That involves developing hardware and software and conducting demonstrations leading to a flight test in fiscal 2023.

One other potential gap in the missile defense architecture is in Pacific-based radars that would have cued GBIs to protect against an attack on Hawaii.

The “Pacific radar is no longer in our budget,” Hill says. Today, forward-deployed AN/TPY-2 radars and a deployable (sea-based X-band) radar work with the GMD system in that region. Plus, Aegis ships can be repositioned, he adds. “We realize we need to take another look at that architecture,” he says, which will focus on the Pacific region.

Missile defense experts are not unsupportive of the effort to build a new NGI. But they do question whether the cost will leach funding for other important priorities.

Frank Rose, a senior fellow at the Brookings Institution, points out that GBIs are built using 1990s technology and as a development prototype tasked for an operational mission. That means that requirements such as reliability, survivability and suitability were afterthoughts.

Despite the sound logic involved in moving toward a new interceptor, “I see a couple of challenges,” he says. That includes that the Pentagon’s budget request was flat for fiscal 2021, a trend likely to continue. In the years ahead, the military will have big bills for its nuclear modernization budget and to recapitalize its conventional forces, which will hit about the time budgets for NGI would need to swell to support procurement of the system.

Meanwhile, in the near-to-midterm,  the U.S. is likely to be dealing with a limited North Korean threat. Over time, the threats will grow in number and sophistication. Given challenges with the budget—not to mention technical challenges with developing a successful kill vehicle—Rose wonders if that money could be applied elsewhere.

Kingston Reif, director of disarmament and threat reduction policy at the Arms Control Association, is skeptical the MDA can deliver an NGI on its current timeline. “Congress must be extremely wary of allowing the Pentagon to repeat the mistakes that have plagued the GMD system in the past,” he says. “In particular, the development, procurement and fielding of the NGI should not be schedule-driven but based on the maturity of the technology and successful testing under operationally realistic conditions. Accelerating development programs risks saddling them with cost overruns, schedule delays, test failures and program cancellations—as has been the case with the GMD program and other missile defense programs to date.”

The expansion of U.S. homeland missile defense may be viewed as a provocation by Russia and China “and likely prompt them to consider steps to further enhance the survivability of their nuclear arsenals in ways that will undermine the security of the United States and its allies,” Reif says. “The costs and risks of expanding the U.S. homeland defense footprint in this way greatly outweigh the benefits.”

But like all proposals, it will be up to lawmakers to decide and is likely to be a point of interest in the year ahead.

“This is the single biggest muscle movement in the 2021 budget proposal, and Congress will be scrutinizing carefully whether the administration has a compelling vision and realistic funding stream for the short, medium and long term,” says Tom Karako, director of the missile defense project at the Center for Strategic and International Studies.