Kim, who by early Monday morning may have been en route to Vietnam by train, could visit industrial plants located between Dong Dang railway station, near the Chinese border in Lang Son, and Hanoi, Japanese newspaper Sankei Shimbun reported.
The North Korean leader, who could cross the Chinese border into Vietnam by late Monday, will need to reach Hanoi by car after arriving at Dong Dang. Travel by car, after Vietnamese authorities block all traffic, would cover more than 100 miles. Yan Pong Hyun Industrial Complex is in the area; the site includes a Samsung Electronics smartphone production plant, according to the Sankei.
Kim visited Chinese manufacturing sites in 2018, including the Beijing Tong Ren Tang plant, a factory that produces Chinese traditional medicines.
The North Korean leader could also pay tribute to fallen North Korean soldiers who fought in Vietnam, the Asahi Shimbun reported Sunday. The ceremony could take place at a memorial dedicated to 14 North Korean soldiers killed in battle. Kim Chang Son, a key North Korean negotiator, has already "inspected" the site ahead of Kim's visit, according to the report.
North Korean officials have conducted checks on other parts of Vietnam, including the tourist attractions in Halong Bay and the industrial zone of Hai Phong.
South Korean news service News 1 reported Monday Kim could stay in Vietnam until March 1 -- which would mean he could be absent from Pyongyang for one week, an unprecedented move for the young leader.
North Korean officials Kim Pyong Hae and Oh Su Yong are also likely to be attending the summit talks. The two men are in charge of economic and administrative affairs, and were not present at the Singapore summit.
Trump has previously hailed North Korea's "tremendous" economic potential.