What truly matters in the THAAD battery destined for Korea is not its weapons, but its AN/TPY-2 X-band radar. Until recently, U.S. officials obfuscated the fact that the radar has two modes of operation: a terminal mode, designed to detect an incoming missile as it approaches its target and trigger the launch of a counter-missile; and a forward-based mode, which can track a missile in its boost phase and pass data back to the U.S.-based anti-missile system. It takes only eight hours to switch the AN/TPY-2 from one mode to the other,