Unlike the so-called Ground-based Midcourse Defense (GMD) system, which is installed in Alaska and California, the THAAD system is not designed to shoot down intercontinental ballistic missiles. The GMD had its own test May 30, intercepting a mock ICBM fired from California.
"This test further demonstrates the capabilities of the THAAD weapon system and its ability to intercept and destroy ballistic missile threats," Missile Defense Agency Director Lt. Gen. Samuel Greaves said in a statement.
He added, "THAAD continues to protect our citizens, deployed forces and allies from a real and growing threat."
The missile agency said this was the 14th successful intercept in 14 attempts for the THAAD system since 2005.
Critics say, however, that the military's testing may not reflect the danger of swarm-type attacks by multiple incoming ballistic missiles from North Korea or other enemies. Such a scenario could overwhelm or confuse the system and render it useless.
"While the THAAD system does have a good number of interceptors, I can imagine it getting overwhelmed by sheer numbers," said Laura Grego, a missile defense expert and senior scientist in the Global Security Program for the Union of Concerned Scientists.
Similarly, Grego said the U.S. military's May 30 test of the "less mature" GMD system designed to protect the U.S. homeland from ballistic missiles has flaws and was "not challenged in the way they would be [in] a real-world scenario."
"We generally say they are scripted for success. They don't have challenging countermeasures of the type that a really dedicated adversary would include," Grego added.
As for South Korea's vulnerabilities to a swarm-like attack, the North is known to have short-range Scud and other missiles targeting Seoul. There's also the possibility of an attack using submarine-launched ballistic missiles, which Pyongyang is believed to have tested at a naval facility on its west coast.