But critics denounced the agreement, accusing the government of making unnecessary promises not to deploy any more THAAD unit or to join the broader US missile defense scheme, nor to form a three-way alliance with the US and Japan.

Joo Ho-young, leader of the Bareun Party, called the deal "humiliating diplomacy."

The government "failed to say confidently that THAAD is an inevitable measure to safeguard our security. Rather, it acted as if making a promise of '3 Nos,'" Joo said during a party meeting, referring to South Korea's assurance that there would be no additional THAAD, no joining the US MD and no Korea-US-Japan alliance. "It's wrong," he concluded.

Joo also criticized the government for failing to point out China's unfair economic retaliation.

"I'd like the government to answer what the difference is between this and the Korea-Japan agreement on the comfort women issue, which the government and the ruling party strongly denounced and demanded be renegotiated," he said.

He was referring to the 2015 deal between Seoul and Tokyo to end years of tensions over Japan's wartime sexual slavery. The so-called "comfort women" agreement has been deeply unpopular in South Korea and the government of then-President Park Geun-hye was criticized for agreeing to never raise the issue again in exchange for compensation without consent from victims. (Yonhap)