The $67 billion missile defense system designed to shoot down North Korean warheads — and protect Hawaii and the mainland in the process — successfully intercepted an intercontinental ballistic missile-class target over the Pacific in a first-of-its-kind salvo test, the U.S. Missile Defense Agency said.

Two ground-based interceptors arced into the sky Monday morning from Vandenberg Air Force Base in California after the “threat-representative” ICBM target was launched from the Reagan Test Site on Kwajalein Atoll in the Republic of the Marshall Islands, over 4,000 miles away.

The “lead” defensive missile destroyed the mock enemy re-entry vehicle, as it was designed to do, the agency said.

The “trail” defensive missile “then looked at the resulting debris and remaining objects, and, not finding any other re-entry vehicles, selected the next most lethal object it could identify, and struck that, precisely as it was designed to do,” according to the agency.

It was one of the most challenging intercepts to date for the nation’s main defense against North Korean missiles — which the Pentagon says continue to pose an “extraordinary threat” to the United States.

Scientists say there’s still a long way to go to develop an effective shield against a raid of North Korean missiles with multiple warheads and decoys.

“This was the first (ground-based interceptor) salvo intercept of a complex, threat-representative ICBM target, and it was a critical milestone,” MDA Director Lt. Gen. Samuel A. Greaves said in a news release. “The system worked exactly as it was designed to do, and the results of this test provide evidence of the practicable use of the salvo doctrine within missile defense.”

Greaves said the ground-based midcourse defense system is “vitally important to the defense of our homeland, and this test demonstrates that we have a capable, credible deterrent against a very real threat.”

China’s and Russia’s nuclear missiles are so sophisticated that they are factored less into the current U.S. missile defense umbrella.

“While the United States relies on deterrence to protect against large and technically sophisticated Russian and Chinese intercontinental ballistic missile threats to the U.S. homeland, U.S. active missile defense can and must outpace existing and potential rogue state offensive missile capabilities,” states the 2019 U.S. Missile Defense Review, which was released in January.

The Pentagon’s chief weapons testing program said in its fiscal 2018 annual report that the ground-based system, with 44 interceptors in Alaska and California, had demonstrated only the capability to defend the U.S. homeland against a “small number” of intermediate-range or intercontinental ballistic missiles with simple countermeasures.

According to the Missile Defense Agency, the ground-based system has had 12 successful flight intercepts out of 20 attempts since 1999. Monday’s test and ones conducted in 2017 and 2014 hit their marks; three successive prior tests did not.

The U.S. Government Accountability Office reported in May that the ground-based missile defense program’s cost exceeded $67 billion, making it the fourth most expensive current weapons system.

In 2020 the Pentagon plans to test a more economical missile, Raytheon’s smaller SM-3 Block IIA, as a possible “underlay” defense against ICBMs. The missile, being co-developed with Japan, has shown promise as a possible defense against long-range ballistic missiles.

The Missile Defense Review called on 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.”