The United States and South Korea have launched official talks on the potential deployment of the U.S. THAAD missile defense system to the South, a Pentagon official said Wednesday.

"I can confirm that the joint working group has met and that consultations are ongoing. The JWG is working 'expeditiously but meticulously,' so no timeline has been established for when consultations will be complete," Cmdr. Bill Urban, a Pentagon spokesman, told Yonhap News Agency.

The spokesman did not provide further specifics, including when the talks were held and how the meeting went, only saying that the working group was formed to "review all aspects regarding the potential deployment of a THAAD system to South Korea."

Shortly after North Korea's Feb. 7 missile launch, South Korea and the U.S. jointly announced they would begin official discussions on the possible placement of the U.S. Terminal High Altitude Area Defense missile defense system in South Korea.

That ended more than a year of soul-searching by Seoul over how to deal with the issue amid Washington's desire to deploy the system and China's intense opposition to it. The North's twin provocations of its fourth nuclear test on Jan. 6 and then a missile test a month later gave Seoul justification for the decision.

China has claimed THAAD could be used against it, despite repeated assurances from Washington that the system is aimed only at deterring North Korean threats. Beijing expressed regret after the South and the U.S. announced the decision to hold THAAD talks.

This week, China's Executive Vice Foreign Minister Zhang Yesui reiterated opposition to the THAAD deployment. (Yonhap)