The initial draft or mark of the House Armed Services strategic forces subcommittee’s part of the fiscal year 2024 defense authorization bill would pull the initial operational capability (IOC) of the hypersonic missile defense program up to 2029, six years faster than current estimates.

During an April hearing, House Armed Services’ Strategic Forces Subcommittee Chairman Doug Lamborn (R-Colo.) disclosed the Defense Department’s FY ‘24 budget request for the Glide Phase Interceptor (GPI), which aims to defend against hypersonic missiles, does not envision reaching IOC until around 2035, which he said is too late (

Defense Daily, April 21).

Concept art of hypersonic missile defense systems. (Image: Northrop Grumman)
Concept art of hypersonic missile defense systems. (Image: Northrop Grumman)

Now the mark of his subcommittee’s section of the bill, published Monday, directs the director of the Missile Defense Agency (MDA) to “carry out a program to achieve, by not later than December 31, 2029, an initial operational capability for the Glide Phase Interceptor.”

The draft defines IOC as an interceptor capable of defeating, in the glide phase, “any IOC endo-atmospheric hypersonic vehicles that are known to Department of Defense and fielded as of the date of the enactment of this Act” with at least 12 GPIs fielded at the time.

During the April hearing, MDA Director Adm. Jon Hill said while the GPI work was still very early and has not even reached Milestone A he acknowledged it could move faster and mid-2030s deployment is too late.

“I believe that we can pull it earlier. It is certainly a funding challenge, but we’ll continue to work closely within the department to pull it as left as possible, because I agree with you that out in the mid 30s is almost irrelevant. We are not meeting the threat,” Hill said.

This draft bill also directs DoD to achieve full operational capability (FOC) by December 2032. 

FOC is defined at defeating any endo-atmospheric vehicles in the glide-phase that are known to DoD and fielded by the time the bill is enacted or that DoD expects to be fielded by 2040. It includes fielding at least 24 GPIs that can “be operated collaboratively with space-based or terrestrial sensors that the Department of Defense expects to be deployed before the end of 2032.”

In 2021 MDA awarded contracts to Raytheon Technologies [RTX], Northrop Grumman [NOC] and Lockheed Martin [LMT] to develop and refine their concepts for GPI (Defense Daily, Nov. 22, 2021).

Then, in 2022, MDA downselected to Raytheon and Northrop Grumman. Both companies have continued to receive modifications to refine their GPI concepts (Defense Daily, June 24, 2022).

As recently as April, the two competitors were awarded modifications that boosted their GPI concept refinement work values to $156 million total for Northrop Grumman and $153 million for Raytheon lasting through March 2024 (Defense Daily, May 1).

Raytheon Missiles & Defense concept art of a potential ship-based Glide Phase Intercept hypersonic defense system. (Image: Raytheon Technologies)
Raytheon Missiles & Defense concept art of a potential ship-based Glide Phase Intercept hypersonic defense system. (Image: Raytheon Technologies)

Relatedly, the bill draft would also authorize the MDA director to enter into a cooperative development agreement with one or more partners of the U.S. for development of GPI FOC. 

This would endorse the work DoD is already exploring for a cooperative development and production work for GPI with Japan, akin to the agreement that has worked with the Standard Missile (SM)-3 Block IIA interceptors.

In March, Hill told reporters MDA was using the same model as with SM-3 IIA, which ideally will offer up propulsion stacks since they currently build the second and third stages of SM-3 IIA because Japan has expressed interest in working to counter hypersonic missile threats (Defense Daily, March 16).

He noted that hopefully U.S. industry will say they want Japan to participate in GPI production with a Japanese company working as a subcontractor. But, if necessary, DoD will repeat its SM-3 IIA contract process that directs the American producer to subcontract with a Japanese company.