No decision has been reached, but earlier this week Lt. Gen. David L. Mann, commander of U.S. Army Space and Missile Defense Command/Army Forces Strategic Command and Joint Functional Component Command for Integrated Missile Defense said such an emplacement would provide a "huge increase in capabilities," in South Korea to protect against threats posed by North Korea.

Mann is aware of China's concerns.

"This is a sensitive issue for the partners throughout the region, and we understand the sensitivities that are involved, especially when you look at South Korea is one of the largest trading partners to China in the region," Mann said. "We don't minimize the sensitivity of these discussions."

Right now, he said, discussions are about the feasibility of putting a THAAD battery in South Korea. The system is designed to strike down incoming missiles in their "terminal" phase. THAAD missiles don't carry warheads, but rather rely on their own weight combined with the speed at which they travel to strike down the missiles they target. A THAAD battery consists of launcher vehicles with each vehicle holding 8 missiles; a radar system; and a fire control system which serves as the communications and data-management backbone.

The THAAD system, he said, is designed to provide greater capability to address "more challenging threat vehicles that are out there." The THAAD system augments existing capabilities such as the Patriot Missile system and the Aegis Combat System.

"THAAD, if you look at its performance, especially in past testing, it's just remarkable what its capability has proven to be," Mann said, praising the system's capabilities.

Were such a system ever put into South Korea, Mann said, it would be focused not on China, but on threats coming from North Korea.