The U.S. Missile Defense Agency said Hawaii is on track within about a year to receive interceptor missiles for North Korean threats — a declaration that marks a dramatic change in the state’s defensive posture.

The Aegis Ashore Missile Defense Test Complex, on Kauai, “can be temporarily activated in the event of a national emergency for operational use,” the agency said.

Previously, the Defense Department said that operationalization would be studied but not necessarily implemented.

The Missile Defense Agency has increasingly acknowledged the capability of a new missile co-developed with Japan that has greater reach and speed, the SM-3 Block IIA, to defend against intercontinental ballistic missiles.

A key first flight test for the SM-3 IIA against a simple ICBM target is expected in May off the coast of Kauai using a Pearl Harbor destroyer to launch the interceptor missile.

The agency now points to the ship- and shore-based missile as part of a possible layered homeland defense with 54-foot ground-based interceptors in Alaska and California taking the first shot at North Korean ICBMs.

The 22-foot SM-3 IIAs could be deployed to protect some U.S. cities as a second chance, while a limited number of Terminal High Altitude Area Defense, or THAAD, batteries, such as one already deployed to Guam, could provide one final shot at defeating incoming ICBMs.

Under the new defensive plan, Hawaii could receive the first emergency protection in the nation using the SM-3 IIA missiles.

The ground-based midcourse defense system in Alaska and California “is capable of defending Hawaii against the current threat of intercontinental ballistic missile attack from North Korea,” the agency said in an email.

But the Aegis Ashore site at the Pacific Missile Range Facility on Kauai can now be temporarily activated for emergency operational use.

“Provided a successful flight test in (fiscal) 2020, a limited layered homeland defense system utilizing the Aegis Weapon System firing SM-3 Block IIA missile will be available for fielding to the Navy by FY 2021,” the agency said.

The defensive system would continue to leverage use of the floating Sea-Based X-Band Radar “to prosecute the mission,” according to the agency.

The Defense Department has re-emphasized the floating radar with plans losing traction for a $1.9 billion Homeland Defense Radar-Hawaii and $1.6 billion Pacific radar expected to be built in Japan.

Funding for both radars was zeroed out in the Missile Defense Agency’s fiscal 2021 budget request — raising speculation that neither of the powerful radars would be built.

The emergence of hypersonic weapons that fly at least Mach 5 — five times the speed of sound, or 3,800 mph, and which can maneuver around radars — has the Pentagon rethinking its sensor architecture and looking to space to cover radar gaps that exist on the ground.

Hawaii’s congressional delegation and U.S. Indo-Pacific Command previously advocated for the Hawaii radar first and foremost, followed by examination of interceptor missiles in the state. But now the radar may be off the table.

Riki Ellison, chairman of the nonprofit Missile Defense Advocacy Alliance, recently said he believed it was “inevitable” that Hawaii would get added ICBM protection in the form of Navy destroyers armed with SM-3 IIA missiles, or activation of the Aegis Ashore test site at the Pacific Missile Range Facility in times of emergency with the new missile.

Hawaii has been underdefended with ground-based missiles needing to come a long way across the Pacific to intercept North Korean ICBMs, Ellison said.

In the short term the Pentagon is “assuming greater risk for Hawaii” without the Homeland Defense Radar-Hawaii, which would have been able to see out in volume and depth, Ellison said.

“It was a tremendously capable radar that would have reduced the (missile) risk to Hawaii,” he said.

The more than $2 billion sea-based radar is able to discriminate ICBM warheads from rocket parts, but it is hampered by a limited field of view likened to looking through a soda straw and need to come into port periodically for maintenance. The ground-based radar in Hawaii would have had what officials call a “persistent” view.

In the meantime, the Pacific has AN/TPY-2 radars, Aegis ship radars and the SBX to handle the sensor load, the Missile Defense Agency said. All are less capable than the Homeland Defense Radar-Hawaii.

Hawaii’s congressional delegation — Sens. Brian Schatz and Mazie Hirono and Reps. Ed Case and Tulsi Gabbard — was asked by the Honolulu Star-Advertiser about the apparent Hawaii radar cancellation.

In a joint statement, the delegation said Secretary of Defense Mark Esper “should be following the advice of the Missile Defense Agency experts who are in the best position to develop the right strategy to keep Hawaii safe. On that, MDA has been clear and consistent: this medium-range discrimination radar is necessary to protect Hawaii from missile threats.

“We will work in the authorizing and appropriating committees to keep this project funded so that MDA can continue to apply a technically sound strategy for protecting all of us.”

The Missile Defense Agency was studying sites at Kaena Point and the Army’s Kahuku Training Area for the Homeland Defense Radar- Hawaii. But after Native Hawaiian opposition arose at the Kaena Point site and community concerns emerged near Kahuku, the agency added the Navy’s Pacific Missile Range Facility as another possible site. Some said it was a last-ditch effort by the agency to secure the radar for Hawaii.

Since then the budget was zeroed out.

“If the Hawaii delegation is serious about the national security imperatives of this radar, their energies might be better directed at the local constituencies who lobbied against it, delayed it and thwarted its construction at the site best suited to the defense of the nation,” said Tom Karako, director of the Missile Defense Project at the Center for Strategic and International Studies.