Yesterday the Missile Defense Agency (MDA) announced a successful test of the Terminal High Altitude Area Defense (THAAD) missile defense system against an intermediate‐range ballistic missile (IRBM) target. This is a significant milestone for the THAAD system, which was recently deployed to South Korea to defend southern cities and the port of Busan against missile attack by North Korea. Even though this particular test was planned months ago, its timing is especially important given North Korea’s successful test of the Hwasong‐12 IRBM in May 2017.
Despite the successful test, it would be dangerous and premature for U.S. policymakers to read too much into THAAD’s capabilities. Initial information about the test suggests that it did not reflect a wartime use of an IRBM by North Korea. Moreover, the test could have negative implications for U.S.-China strategic stability.
Based on the statement released by the MDA and video of the test, the test seems to have been relatively easy for THAAD. For example, at the moment the warhead is intercepted it does not seem close to any other objects. This makes it relatively easy for THAAD’s infrared sensor to locate the warhead and slam into it. However, it would be much harder for the sensor to locate the warhead if the target missile broke up in flight and cluttered the sensor. It is not clear whether the target missile used in the most recent test broke up in flight, but based on past tests it seems unlikely. This makes for successful testing, but it does not reflect real‐world scenarios.