The United States says it still plans to test a missile defense system known as THAAD mere days after North Korea test-launched a long-range missile potentially capable of delivering a nuclear warhead to the western United States.
The U.S. test, first revealed to Reuters by unnamed sources and planned months ago, will use interceptors stationed in Alaska, a location on the front lines of a potential attack by North Korea.
The THAAD system—it stands for Terminal High Altitude Area Defense—is primarily built by Lockheed Martin. It has a 100% success rate in 13 tests stretching back to 2006, reflecting vast technological advances since Ronald Reagan first pushed for missile interceptor technology in 1983. U.S. missile defense as a whole, however, is still considered unreliable by many.
Get Data Sheet, Fortune’s technology newsletter.
Missile defense, originally conceptualized as a system of space-based lasers, was a politically dicey threat to the balance of Cold War power, and it remains internationally contentious today. Both China and Russia have objected to the U.S. deployment of THAAD systems in South Korea, and new South Korean President Moon Jae-in temporarily halted a related rollout in June.
The new THAAD tests are highly symbolic. In addition to the clear threat from North Korea, the tests point to waning U.S. patience with China, which has supported North Korea to maintain regional stability and counterbalance Western influence. China’s president Xi Jinping has publicly opposed North Korea’s actions but resisted taking steps to deter further escalation.