Chinese Foreign Minister Wang Yi raised this issue during a meeting with his South Korean counterpart Park Jin on Tuesday. Beijing said the deployment of the U.S. Terminal High-Altitude Area Defense (THAAD) system and its radar capabilities would undermine China’s “strategic security interest.”

According to the Chinese Foreign Ministry, the two sides agreed in the talks to take “the legitimate concerns” of both countries to ensure that the THAAD issue will not become a “stumbling block” in their bilateral relations.

Wang also urged the new South Korean government of conservative Yoon Suk-yeol to honor the left-leaning Moon Jae-In administration’s “Three Nos” policies, which stated that Seoul wouldn’t deploy any additional THAAD systems, wouldn’t participate in U.S.-led missile defense networks, and wouldn’t form a trilateral military alliance with Washington and Tokyo.

However, the Yoon administration’s Foreign Ministry has responded, saying that the previous administration’s “Three Nos” pledge was not a formal agreement.

“During the meeting, both sides confirmed their differences over the THAAD matter, but also agreed that the issue should not become an obstacle that influences relations between the countries,” the South Korean side said its statement following the meeting.

Yoon’s office said that South Korea deployed the THAAD system mainly to counter the missile threat posed by aggression from North Korea, and that the past administration had provided no material regarding its pledge with China, according to local media Yonhap News Agency.

“Our government clearly states that THAAD is a self-defense tool aimed at protecting our people’s lives and safety from North Korea’s nuclear and missile threats and a matter of security sovereignty that can never be subject to negotiation,” it added.

South Korea deployed the THAAD system in 2017 in response to Pyongyang’s nuclear program. But China claimed that the THAAD system could be reconfigured to peer into its territory and retaliated by suspending Chinese group tours to South Korea.

South Korea Stands Firm on Installing the THAAD Missile Defense System

Former President Moon, who together with former U.S. President Donald Trump pursued engagement with North Korea for the denuclearization of the Korean Peninsula, also tried to repair relations with Beijing by pledging the “Three Nos.”

Moon’s dovish approach has been discarded by his successor, Yoon, who has vowed stronger security cooperation with Washington and expressed a willingness to acquire more THAAD batteries to counter North Korea’s nuclear threats.