"[US National Security Adviser] John Bolton and Secretary of State Mike Pompeo continue to tell North Korea that there will be no easing of sanctions until complete denuclearisation. North Korea, most likely, will not negotiate with the United States under these conditions", Moon said.
According to the adviser, Washington should send a clear message to Pyongyang that its intentions are friendly.
"The United States should make a gesture, showing that it is going to reduce tensions, that it has no hostile intentions towards North Korea", the adviser said.
US President Donald Trump is paying an official visit to South Korea from 29-30 June. On Friday, the US president via Twitter also invited North Korea's Chairman Kim Jong-un to meet him at the demilitarized zone (DMZ) in the coming days.
Kim and Trump have been engaged in talks aimed at denuclearising the Korean Peninsula for months. In June 2018, the two heads of state expressed commitment to denuclearisation at a landmark bilateral meeting in Singapore. The next round of talks, held in February in Vietnam, however, ended abruptly without any agreement.