The U.S. Missile Defense Agency said it conducted its 15th successful intercept in 15 tests of the Terminal High Altitude Area Defense system.

A medium-range target ballistic missile replicating a North Korean threat was air-launched Saturday, Hawaii time, by a U.S. Air Force C-17 cargo plane over the Pacific.

“The THAAD weapon system located at Pacific Spaceport Complex Alaska in Kodiak, Alaska, detected, tracked and intercepted the target,” the Missile Defense Agency said.

Soldiers from the 11th Air Defense Artillery Brigade conducted launcher, fire control and radar operations using the same procedures they would use in an actual combat scenario, the agency said. Soldiers operating the equipment were not aware of the actual target launch time, officials said.

It was the second successful THAAD intercept test in three weeks and bolsters confidence in the defensive system that’s deployed to South Korea and Guam.

Following North Korea’s second successful intercontinental ballistic missile test Friday, South Korean President Moon Jae-in ordered talks with the United States on deploying four more THAAD launchers in addition to the two already activated. Each of the truck-mounted launchers has eight missiles.

The THAAD tests were scheduled before North Korea’s latest provocations.

The mobile THAAD system can be used to intercept ballistic missiles inside or outside the atmosphere in the terminal, or final, phase of flight.

“Intercepting a warhead during this phase is difficult and the least desirable of the phases because there is little margin for error and the intercept will occur close to the intended target,” the Missile Defense Agency said on its website.

On July 11 a ballistic missile target simulating an intermediate-range North Korean threat was launched by aircraft north of Hawaii and successfully intercepted by a THAAD missile.

Medium-range ballistic missiles travel up to 1,864 miles, while intermediate-range missiles can fly up to 3,418 miles.

THAAD was tested multiple times out of the Pacific Missile Range Facility on Kauai starting in 2007. Earlier this year the Missile Defense Agency said it wanted to shift THAAD testing to Alaska’s Kodiak Island.

When North Korea announced the planned test of a long-range rocket in 2009 with an azimuth in the direction of Hawaii, then-Defense Secretary Robert Gates said he had “directed the deployment” of THAAD missiles in the state and ordered the Sea-Based X-Band Radar to sea to “provide support.”