Hawaii may become the first state in the nation to get a new type of ground-based missile interceptor — in addition to the powerful $1 billion radar that’s already in the works — to better protect against North Korean missile attack.

A long-awaited Missile Defense Review recently released by the Pentagon calls for the Missile Defense Agency and the Navy to study the viability of “operationalizing” the Aegis Ashore missile defense test site on Kauai, either temporarily or permanently, with interceptor missiles.

The Defense Department “will study this possibility to further evaluate it as a viable near-term option to enhance the defense of Hawaii,” the Missile Defense Review states. “The United States will augment the defense of Hawaii in order to stay ahead of any possible North Korean missile threat.”

The military also was ordered to develop an “emergency activation plan” that would enable the defense secretary to activate the Aegis Ashore site in 30 days.

Some defense experts have called for the operationalization of the Aegis Ashore site — now a testing facility — for several years, claiming a gap exists when it comes to the defense of Hawaii under the nation’s missile protection umbrella.

But members of Hawaii’s congressional delegation accepted the Navy and Missile Defense Agency position that a powerful discriminating radar to better identify incoming missiles was needed first, followed by a review of whether missile interceptors were needed.

The Missile Defense Review findings — put together with wide-ranging and high-level input — came as a surprise and upended the previous Hawaii plan by moving up active examination of defensive missiles possibly being located in the state. The study called the Aegis Ashore plan a “repurposing” opportunity to boost missile defense.

A tandem concern for Hawaii’s lawmakers was the possible affect that missile defense activation might have on jobs, regular testing and community access at the Pacific Missile Range Facility on Kauai where Aegis Ashore is located.

“Our main objective is to protect the homeland and our home in Hawaii. To do that, we must rely on the experts,” U.S. Sen. Brian Schatz, a Hawaii Democrat, said in an email.

The Missile Defense Agency, U.S. Indo-Pacific Command and other military components “continue to assess the best combination of radars and defensive interceptors to protect us from rogue threats.”

Schatz said that “our job as elected officials is not to just substitute our judgment for that of the experts. Our job is to hear from them, exercise our oversight duties and provide the funding that keeps us safe.”

“Whatever we do must maintain PMRF’s capacity to continue as the premier missile-testing range on the planet,” he said.

Riki Ellison, chairman of the nonprofit Missile Defense Advocacy Alliance, has been a frequent proponent of using Aegis Ashore for the active defense of Hawaii.

All 50 states have limited protection from enemy intercontinental ballistic missiles via 40 ground-based interceptors in Alaska and four in California.

However, the remoteness of Hawaii means the U.S. military has a one-shot chance of protecting the state from a rogue missile, while other states could have shoot-look-shoot multiple options for defense with what amounts to a very limited supply of the current interceptors, Ellison said.

By activating Aegis Ashore with eight newer and smaller SM-3 Block IIA missiles now in testing, even just in emergency situations, “you’ve got your own missiles to protect you, which is much better off than have a president say, ‘Hey, I’m going to protect Boston, I’m going to save these (bigger missiles) to protect L.A.,’ and let Hawaii go — which is what it is today,” Ellison said.

The nation’s missile defense plan was last updated in 2010. The new review was initiated in 2017. The report notes that China and Russia are developing advanced cruise missiles and hypersonic weapons. North Korea, with nuclear-armed ballistic missiles, “continues to pose an extraordinary threat.”

Kauai’s Aegis Ashore facility derives from ship-based Aegis weapons systems that are capable of shooting down shorter-­range ballistic missiles.

A new missile being co-developed by the United States and Japan, the SM-3 block IIA, has considerably more range and speed and is expected to be a match for North Korean or Iranian ICBMs.

Kauai’s Aegis Ashore was put in place to test a similar facility in use in Romania and another planned for Poland. Japan has ordered two of the ashore sites for $2.15 billion.

The United States plans to increase its ballistic missile defense destroyers — which could protect Hawaii with SM-3 IIAs — but Chief of Naval Operations Adm. John Richardson said at a forum Monday that ships are designed as a maneuver force, and if a land asset is going to receive long-term protection, “then let’s build something on land and protect that and liberate these ships from that mission.”

Ellison noted the Kauai Aegis Ashore has been used to fire live SM-3 IIA missiles before — most recently on Dec. 11, when an intermediate-range target missile launched “thousands” of miles away was successfully intercepted by one of the land-launched SM-3 IIAs.

The first test against a longer range ICBM target is expected by 2020.

Ellison said some military officials convinced Hawaii’s congressional delegation that operationalizing Aegis Ashore at PMRF “would shut the base down. But that’s not true.”

In an emergency, a crew of 30 could be flown in and defensive missiles could be moved from Pearl Harbor and loaded into the eight-missile launcher with 24- or 48-hour advance notice, he said.

Ellison also said the launcher site could be moved to have less impact on the base, or even relocated to a barge at sea.

The Missile Defense Agency was not able to provide immediate comment.

In an email, U.S. Sen. Mazie Hirono said, “I remain a steadfast supporter of investments like the Homeland Defense Radar-Hawaii that will help to better detect threats to our state, and ensuring that Kauai’s Pacific Missile Range remains capable of providing the test range capabilities and support the military deems necessary.”

The $1 billion radar, with an 80-foot face, may be built at Kaena Point. Construction is expected to start in 2021 with initial operating capability expected late in 2023.