"The U.S. was deeply disgruntled by Seoul's offer for military talks," he said during a ceremony marking the 10th anniversary of the second inter-Korean summit on Oct. 4, 2007. "U.S. Secretary of State Rex Tillerson lodged a complaint to Foreign Minister Kang Kyung-wha in harsh tones."
This is the latest indication that there may be a gap between the Moon and Donald Trump administrations on how to handle North Korea.
At the ceremony later, President Moon renewed his call for inter-Korean military talks.
"Military dialogue should be resumed urgently to ease tensions between the two countries," he said, noting that it was one of the agreements reached during the historic summit.
The largest conservative Liberty Korea Party (LKP) has accused the Moon administration of failing to coordinate with the U.S. over how to deal with North Korea, saying it reflects the chasm growing in the South Korea-U.S. alliance.
"The government has dismissed our concerns on the alliance with the U.S. But now with Moon's remarks, we have to wonder if mistrust between the two countries is taking the bilateral relations to a dead end," LKP floor leader Chung Woo-taik said.
The Moon Jae-in government proposed in July that the two Koreas resume military and Red Cross talks, as part of efforts to implement a peace overture delivered in a previous presidential speech in Berlin. Pyongyang, however, did not respond until the proposed date.
At that time, the Ministry of Foreign Affairs said it had sufficiently explained the proposal to the U.S. and sought understanding in advance.
Moon, the presidential special envoy, supported the government's calls for inter-Korean military talks during his special speech, and also proposed the U.S. send a special envoy to North Korea to alleviate growing tensions on the peninsula.
"It is most ideal if President Trump sends his special envoy to the North and they both make a secret deal," he said. "Along with this, inter-Korean talks are necessary to contain a possible war, which is likely to follow an accidental clash along the Demilitarized Zone or in the West Sea."
But for the timing of the talk with the North, he remained skeptical, saying a change in Pyongyang's bellicose stance should come first.
"It seems difficult to open dialogue at this stage. I hope North Korea makes some effort on its part," he said. "If North Korea refrains (from missile and nuclear tests) and gives a bit of breathing room to inter-Korean relations, we can immediately implement the 28 accords in the Oct. 4 Inter-Korean Joint Declaration."
Moon, a Yonsei University professor, attended inter-Korean summits held in North Korea as a special aide to Presidents Kim and Roh in 2000 and 2007.
Moon earlier caused a stir with a controversial remark where he suggested a willingness to reduce the scale of joint military exercises between the U.S. and South Korea, and the frequency of the dispatch of strategic assets to the peninsula, if North Korea suspended its nuclear and missile programs.
He stressed before the speech that it was a personal opinion, not an official position of the Moon government. "I'm speaking as a professor today, not as Moon's special envoy," he said.