WASHINGTON -- New video released by the Pentagon shows the successful test of a missile defense system meant to protect against an intercontinental ballistic missile (ICBM) under development by North Korea.

The video shows the launch of a target missile from the Kwajalein Atoll in the Marshall Islands on Tuesday, followed by a shot of an interceptor missile launching from a silo at Vandenberg Air Force Base in California.

Infrared footage shows the collision between the missile and the interceptor.

Infrared footage shows a successful intercept of a mock warhead on Tuesday, May 30, 2017. Missile Defense Agency

Vice Adm. Jim Syring, director of the Missile Defense Agency, said the successful test represented a specific real-world scenario, CBS News national security correspondent David Martin reports.

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Pyongyang is understood to be moving closer to the capability of putting a nuclear warhead on such an ICBM and could develop decoys sophisticated enough to trick an interceptor into missing the real warhead. The target missile used in Tuesday's test deployed decoys meant to throw the interceptor missile off its trail.

Syring said in a briefing that the main difference between the test and a North Korean missile launch was the location of the test, which was conducted much further south in the Pacific than the trajectory of a potential North Korean strike. As a result, radar systems in Japan and Alaska weren't in use during the test.

The successful test was hailed as a triumph, with Syring saying the result was "an incredible accomplishment" that marked a critical milestone for a missile defense program hampered by setbacks over the years.

However, Syring's agency also sounded a note of caution after the $244-million test.

"Initial indications are that the test met its primary objective, but program officials will continue to evaluate system performance based upon telemetry and other data obtained during the test," an earlier written statement said.

In Tuesday's U.S. test, the Pentagon's Missile Defense Agency launched an interceptor rocket from an underground silo at Vandenberg Air Force Base in California. The target was an intercontinental-range missile fired from a test range on Kwajalein Atoll in the Pacific.

According to the plan, a 5-foot-long "kill vehicle" released from atop the interceptor zeroed in on the ICBM-like target's mock warhead outside Earth's atmosphere and obliterated it by sheer force of impact, the Pentagon said. The "kill vehicle" carries no explosives, either in testing or in actual combat.

The target was a custom-made missile meant to simulate an ICBM, meaning it flew faster than missiles used in previous intercept tests, according to Christopher Johnson, the Missile Defense Agency's spokesman. It was not a mock-up of an actual North Korean ICBM, and details of its exact capabilities weren't made public.

Officially known as the Ground-based Midcourse Defense system, the Pentagon likens the defensive tactic to hitting a bullet with a bullet. With congressional support, the Pentagon is increasing by the end of this year the number of deployed interceptors, based in California and Alaska, to 44 from the current total of 36.

While Tuesday's test wasn't designed with the expectation of an imminent North Korean missile threat, the military wants progress toward the stated goal of being able to shoot down a small number of ICBMs targeting the United States.

Laura Grego, senior scientist at the Union of Concerned Scientists, which has criticized the missile defense program, called the interceptor an "advanced prototype," meaning it is not fully matured technologically even if it has been deployed and theoretically available for combat since 2004. A successful test Tuesday, she said, could demonstrate the Pentagon is on the right track with its latest technical fixes.

"Overall," she wrote in an analysis prior to the test, the military "is not even close to demonstrating that the system works in a real-world setting."

The interceptors are, in essence, the last line of U.S. defense against an attack by an intercontinental-range missile.

The Pentagon has other elements of missile defense that have shown to be more reliable, although they are designed to work against medium-range or shorter-range ballistic missiles. These include the Patriot missile, which numerous countries have purchased from the U.S., and the Terminal High-Altitude Area Defense, or THAAD, which the U.S. deployed this year to South Korea to defend against medium-range missiles from North Korea.