The United States' secretary of state said on Thursday in Seoul that North Korea sanctions will only be lifted after complete denuclearization is achieved.

Mike Pompeo stressed in a press conference held after a meeting with his South Korean and Japanese counterparts Kang Kyung-wha and Taro Konom that the US government is committed to "complete, verifiable and irreversible denuclearization" of Pyongyang.

Pompeo said the sanctions on North Korea will only be relieved after complete denuclearization of the Korean Peninsula is achieved and added that Kim "understands the urgency" of the process, according to South Korea's Yonhap news agency. He assured this will be implemented on a "sequencing, conditions" basis.

Pompeo answered questions regarding the vague terms used in the agreement signed by Trump and Kim at the end of the summit.

Kim and Trump signed an agreement in which they pledged to open a new chapter of relations, establish "a lasting and stable peace" and work towards North Korea's complete denuclearization.

No concrete mechanisms or deadline were mentioned in the agreement.

When asked about the possible suspension of the US-South Korea joint military maneuvers proposed by Trump at the end of the summit, South Korea's foreign minister Kang said it should be carefully decided by respective defense authorities.

North Korea considers these exercises an attempt invade its territory.

Pompeo met with South Korean President Moon Jae-in on Thursday to discuss the results of the Jun. 12 summit. He is scheduled to visit Beijing later the same day to brief the Chinese authorities on the post-summit details.