South Korean President Moon Jae-in on Tuesday tapped a former official who was deeply involved in the 2007 inter-Korean summit to be his point man on North Korea as he seeks a new approach to Pyongyang.
"The North has already conducted a number of experiments to test various elements of the missile", she said.
Moon has sought to expand cross-border civilian exchanges as a way to improve ties, but North Korea on Monday rejected a Seoul civic group's offer to provide anti-malaria supplies to protest South Korea's support of fresh United Nations sanctions adopted last week.
THAAD's deployment has been a polarizing issue for most of the region.
Citing "escalating confrontation and heightened risks of catastrophic conflict" on the Korean peninsula, the World Council of Churches has called for the lifting of sanctions against North Korea. The Joint Chiefs of Staff said a thorough investigation will be made of the object found south of the Demilitarized Zone that bisects the Koreas.
Under increased pressure from the USA and China, the sole North Korean concession of the past year has been its hesitation on testing another nuclear device.
Japan wants South Korea to remove a statue near the Japanese consulate in Busan city commemorating Korean comfort women as well as another near the Japanese embassy in Seoul, saying that the presence of the statues violate the 2015 agreement.
Experts have long suggested that North Korea intends to develop a thermonuclear bomb that can reach hold targets in the USA mainland at risk as a deterrent, for possible diplomatic concessions, and now, to prove wrong a tweet from President Donald Trump.
In its latest act of provocation, North Korea launched last Thursday a series of short-range missiles that flew about 200km.
It added that it was a mistake to think that sanctions could not succeed against a country like North Korea, which was less isolated than it appeared.
A South Korean Defence Ministry official confirmed to Reuters that the device took at least 10 photographs of the anti-missile system - known as the Terminal High Altitude Area Defense (THAAD).