Like the Patriot anti-missile defences, the Terminal High Altitude Area Defence, or Thaad, system is designed to knock out ballistic missiles in their final minute of flight.
Unlike the Patriot system, however, it is designed to intercept targets at higher altitudes, allowing it to defend a larger area.
When fully implemented, the Thaad system "will provide high-altitude missile defence over a larger area than the complementary Patriot system", Lieutenant General Henry Obering, missile defence agency director, said in a statement.
Patriot missiles - first widely used during the Gulf War - are short-range missiles designed to protect ground forces from enemy missiles when they are in their "terminal phase," or closer to hitting its target.
Pam Rogers, a missile defence agency spokeswoman, said the new system is designed to complement Patriot defences, not replace them.
The Thaad system had its first successful test last year at White Sands Missile Range in New Mexico. It had another successful test on January 27 in Hawaii.
The missile defence Agency moved its Thaadd testing to Hawaii because the New Mexico testing range was not large enough for the military to do the testing it wanted, Rogers said.