Russia's TASS news agency reported hours earlier that Kim departed from the North Korean capital of Pyongyang on his personal train.
According to state officials, Trump spoke to Prime Minister Shinzo Abe via telephone last Wednesday prior to the Vietnam summit with Kim.
The Communist Party's mouthpiece Nhan Dan newspaper late Friday quoted Vietnam's Department of Roads as saying the ban will first apply to trucks 10 tons or bigger, and vehicles with nine seats or more on the 170-kilometre (105-mile) stretch of Highway One from Dong Dang, the border town with China, to Hanoi from 7 p.m. on Monday to 2 p.m. on Tuesday, followed by a complete ban Tuesday on all vehicles from 6 a.m.to 2 p.m.
The Vietnamese foreign ministry announced on Saturday Kim would "pay an official visit in the coming days", ahead of the summit though no details were released.
Last year, North Korea suspended its nuclear and long-range missile tests and unilaterally dismantled its nuclear testing ground and parts of a rocket launch facility without the presence of outside experts, but none of those steps were seen as meaningful cutbacks to the North's weapons capability.More news: Lawyer: Ex-FBI official McCabe still facing investigation
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First, Trump will meet the soon-to-be enthroned 126th emperor of the world's oldest monarchy, Crown Prince Naruhito, who is set to ascend the throne on the first week of May. Vietnamese police have stepped up security around the border station ahead of Kim's arrival.
Two sources with direct knowledge of security and logistics planning told Reuters on Wednesday that Vietnam was preparing for Kim to arrive by train.
It is not known if he will travel by train from Pyongyang via China or fly to a nearby Chinese city. Kim traveled to Singapore on a plane lent to him by China.
The Trump administration has pressed North Korea to give up its nuclear weapons program, which threatens the United States, before it can expect any concessions.
His predecessors, father Kim Jong Il and grandfather Kim Il Sung, also preferred rail for their domestic and overseas travels. In conjunction with the US-North Korea summit, Kim and Trong are expected to meet for talks, among events related to bilateral ties.
They said the Metropole Hotel would be a backup location for the summit and Kim could possibly stay in the Melia hotel.