US Secretary of State Mike Pompeo said President Donald Trump has been “incredibly clear” about the sequencing of denuclearization and relief from the sanctions.
"We are going to get complete denuclearization; only then will there be relief from the sanctions," Pompeo told reporters after meeting with South Korea's president and Japan's foreign minister in Seoul on Thursday, presstv Reported.
According to North Korean state media, the country's leader Kim Jong-un and President Trump had agreed during their Singapore summit held June 12 on the principle of "step-by-step and simultaneous action" to achieve peace and denuclearization on the Korean Peninsula.
Pompeo said step-by-step “sequencing” meant that “denuclearization” will take place first, and will then be followed by “sanctions relief."
During the summit, Kim conditioned denuclearization upon the cessation of hostility between Pyongyang and Washington.
The statement issued at the end of the summit provided no details as to when North Korea would renounce its nuclear weapons or how the dismantling might be verified.
Media reports suggested that South Korea and Japan were worried that the lifting of sanctions on the North would ease pressure on Pyongyang.
Meanwhile, a senior South Korean presidential official said on Friday that the presence of US military forces in South Korea was not subject to the Washington-Pyongyang negotiations and that it was a matter related to the US-South Korean alliance.
"Let me be clear. There has been no discussion and no change in position on the matter of the issue of US troops in South Korea," said the senior South Korean official, who spoke on condition of anonymity.
The official also said there had been discussions between North Korea and the United States before Tuesday's summit about completing an "early" denuclearization of the Korean Peninsula. The high-level official did not elaborate.
The official said the summit had "jump-started" the stalled denuclearization talks.
On Wednesday, Trump said the United States was stopping its “provocative” and expensive joint military exercises with South Korea to facilitate denuclearization talks with North Korea.
North Korea sees the joint war games, which include land, naval and air drills as well as cyber warfare as a threat to its national security.
Around 28,500 US troops are stationed in South Korea.