The Pentagon has called THAAD a “critical measure” to defend South Koreans and U.S. forces and the top U.S. commander in the Pacific, Admiral Harry Harris, said the system would be operational “in coming days.”

Seonjgu residents have protested, citing safety fears and its potential to be a wartime target. President Trump and Defense Secretary James Mattis have said all options are on the table to counter what Harris called "the reckless North Korean regime" in his testimony Wednesday before the House Armed Services Committee. But Harris also stated, "We want to bring Kim Jong Un to his senses, not to his knees." U.S. Department of Defense, Missile Defense Agency/Handout via Reuters/File Photo

Trump told Reuters in an interview on Thursday he wants South Korea to pay for the $1 billion Terminal High Altitude Area Defense (THAAD) system. "The overnight, unannounced operation came just six days after U.S. Forces Korea (USFK) secured the land in Seongju, North Gyeongsang Province, from the South Korean government," the Yonhap News Agency reports. Large components of the U.S. THAAD system began landing in South Korea early last month, under an agreement that was reached last July. Wednesday's convoy of trucks and equipment included some 20 trucks, the Korea Herald reports, adding, "Although covered by plastic boxes and wrapping, they were believed to include a radar, launchers, interceptors, a fire control and communications unit, a power generator and a cooler." North Korea conducted live-fire artillery drills and a US guided-missile submarine arrived in South Korea on Tuesday, as the Trump administration prepared what Mr Baucus called an "extraordinary" White House briefing for all 100 senators on the escalating nuclear threat. Related: South Korean company to China: Don't blame us for THAAD missiles

China has vigorously opposed the stationing of the THAAD anti-missile system in South Korea, complaining that it threatens security and fuels tensions in the region. “We want to retain THAAD in our arsenal, consistent with all other U.S. weapons systems deployed on the Korean peninsula. The U.S. says the THAAD system is not an offensive weapon — a point that Adm. Harris reiterated on Capitol Hill on Wednesday. "This system is a defensive system that will help protect South Korea from ballistic missile attacks from North Korea," Harris told the House committee during Wednesday's public hearing. "It is a purely defensive system," he added, saying that the THAAD components are "aimed north" — not at China to the west. Harris said that he takes Kim Jong Un at his word when he threatens U.S. targets. The leader has previously spoken of striking American cities, and this week, North Korea threatened to sink the USS Carl Vinson aircraft carrier. "I believe that we have to look at North Korea as if Kim Jong Un will do what he says," Harris told the panel, while acknowledging that for now, at least, there's a "capability gap" between what the North Korean leader has threatened and what his military could achieve. But when that gap is closed, Harris also said, it would represent an "inflection point, and we're going to have to deal with that, I believe." In South Korea, the deployment has stirred a mix of reactions, including protests and clashes with police Wednesday. "South Korean television showed images of demonstrators in rural Seongju county, about 155 miles south of the capital, hurling water bottles at trucks carrying parts of the THAAD system," reporter Jason Strother tells NPR from Seoul. "Reports say protesters tried to block its delivery to a golf course that's being converted into a base."
A South Korean adviser says it is "impossible" for South Korea to purchase the THAAD missile complex since control of its operation would remain with the United States. The remarks come after United States president Donald Trump suggested that South Korea pay for the $1 billion system.