The Missile Defense Agency confirmed it is looking at the possibility of siting a $1.9 billion Homeland Defense Radar-Hawaii at the Pacific Missile Range Facility on Kauai instead of at one of several spots on Oahu that had been considered since 2018.

Native Hawaiian cultural challenges at a Kaena Point candidate site and topographical obstacles there and at two possible sites at Kahuku Training Area — all on Oahu — led the agency to remove Kahuku Training Area site 2 from consideration and add Kauai to the mix.

The revisions mean that construction isn’t expected to start until 2023, with the buildout expected to take three to five years — significantly delaying the radar that was originally planned to have initial operating capability for the increased defense of Hawaii from North Korean threats in 2023, according to officials.

In coordination with U.S. Indo-Pacific Command, the Missile Defense Agency “is currently revisiting the viability” of fielding the radar on Defense Department property at the Pacific Missile Range Facility, MDA spokeswoman Heather Cavaliere said in an email.

“In October 2019, MDA began conducting analyses and studies at PMRF locations not previously explored in the siting analysis,” she said. “This effort is ongoing and MDA expects to make a site suitability determination in March-April 2020.”

If a suitable site at the Pacific Missile Range Facility is identified, it will be incorporated into an environmental impact statement for full analysis along with the remaining candidate sites on Oahu, she said.

“It is our understanding that the U.S. Missile Defense Agency has been conducting preliminary studies to determine whether there is a suitable site on PMRF for a high-powered ballistic missile defense radar as mandated by Congress,” Kauai Mayor Derek S.K. Kawakami said in a statement. “PMRF has not yet been included in the MDA’s environmental impact statement for the project, therefore we do not have enough information on how a potential radar could affect our island’s environment and community.”

A 2018 state notice announcing the environmental impact statement process said the use of the 160-acre Kahuku Training Area site 2 would require deconstruction and relocation of an existing Naval Research Laboratory facility that would be in the new radar’s viewplane.

The 160-acre Kahuku Training Area Site 1 at a 400-foot elevation remains in the running, along with one up high on Kuaokala Ridge adjacent to the Air Force’s Kaena Point Satellite Tracking Station. All the sites face East Asia.

Native Hawaiian cultural concerns emerged at the Kuaokala Ridge site, while community worries were raised about overdevelopment at the two other candidate sites at the Army’s 9,500-acre Kahuku Training Area.

Some Native Hawaiians threatened to protest should the Kuaokala site be selected.

Additionally, while conducting initial design studies, the Missile Defense Agency “found that site constructability is challenging at all three proposed locations on Oahu. Each alternative site has extreme topographical features that require extensive site preparation prior to construction,” Cavaliere said.

State of Hawaii review processes to access state land for geotechnical studies needed to plan construction at Kaena Point took eight months longer than originally planned, meanwhile, she said.

The Hawaii radar is intended to reach farther out to identify and discriminate warheads from rocket parts and decoys sooner amid a proliferation of increasingly sophisticated ballistic missiles.

“The projected missile threat is complex and volatile, and it includes evolving ballistic and hypersonic missile threats,” MDA Director of Operations Michelle Atkinson said at a news briefing in March. “It is critical that we continue to develop innovative and breakthrough technologies to outpace rogue state offensive missile capabilities.”

Congress has said the Hawaii radar is intended to “close coverage gaps” in the Pacific architecture. A high-power radar is being built in Alaska, and the Pentagon has plans for an additional Pacific radar. Space-based sensors also are being aggressively pursued.

The delay raises questions about the viability of the Hawaii project and the defense of the state from North Korean threats when U.S. Indo-Pacific Command previously said it wanted to pursue the advanced radar before considering dedicated interceptor missiles here.

Now the suitability of PMRF as a potential site for the Homeland Defense Radar-Hawaii has been added to the mix.

A missile launch is planned at the PMRF range in coming months to test for the first time the ability of a new ship-based SM-3 Block IIA missile to intercept an intercontinental ballistic missile target — which will have significant implications for the potential defense of Hawaii.

The missile already has been test-fired against an intermediate-range target from what’s known as an “Aegis Ashore” site at PMRF that replicates ship-based capabilities.

The 2019 Pentagon Missile Defense Review states that a “repurposing option” for the Aegis Ashore test site on Kauai is to either temporarily or permanently “operationalize” it with interceptor missiles to enhance the defense of Hawaii.

All the possible changes come amid Navy concerns over potential conflicts with regular testing at PMRF, which has the largest instrumented range in the world for submarine, surface ship and missile defense testing.

“If we were to look at the fiscal year for ‘20 and ‘21, our calendar is packed, supporting MDA, supporting other organizations, hypersonics, direct energy, on the test side of the house,” Capt. Tim Young, PMRF’s commander, said earlier this month.

With joint and unit-level training all the time on the range as well, “I can tell you it is fully utilized 24-7 most days out of the year,” Young said.