US President Donald Trump's blitz meeting with North Korean leader Kim Jong Un at the demilitarised zone (DMZ) between the Korean nations on June 30 was planned ahead by the two sides, the Asahi reported, citing unnamed US and North Korean diplomats.
Mr Trump suggested the DMZ meeting in a letter to the North Korean leader, which was sent to Pyongyang in June by a senior US official, the Japanese newspaper said.
The North Korean side agreed to give a "sign" if the meeting were to go ahead, according to the report.
White House Press Secretary Sarah Huckabee Sanders confirmed in a statement that month that a letter was sent by the president. Mr Kim said the letter had "excellent content," state media KCNA reported at the time.
The day before the summit, while in Japan for the G-20 gathering, Mr Trump tweeted about his willingness to cross the border to meet Mr Kim.
He said he "put out a feeler" and that he didn't know where Mr Kim was at the time. Hours later, North Korean diplomat Choe Son Hui called Mr Trump's tweet "a very interesting suggestion."
According to Asahi, that was the signal to the US special envoy to North Korea, Stephen Biegun, to begin preparations for the meeting.
While Mr Trump has met Mr Kim twice before at summits in Singapore and Hanoi, no US president had ever sat down with a North Korean leader at the DMZ.
Mr Kim said he was "surprised" by Mr Trump's request to meet, and called the US president's short walk over the demarcation line into North Korea "a very courageous and determined act."
