North Korean leader Kim Jong Un took a 2-1/2-day train trip to Hanoi, Vietnam, where he is scheduled to meet US President Donald Trump for their second summit.

Experts say his reasoning for taking such a slow means of transport may be to show he is not overly reliant on China.

Kim took an Air China plane to his summit with Trump in Singapore in June, which led to commentary emphasizing his inability to fly himself there.

Those comments reportedly didn't sit well with Kim.

North Korean leader Kim Jong Un is taking a 2,000-mile, 2-1/2-day train ride to meet US President Donald Trump in Vietnam this Wednesday, most likely to save face because he doesn't want to ask China to lend him a plane.

Kim boarded his family's armored train at Pyongyang Station on Saturday evening, and he arrived in the Vietnamese capital of Hanoi on Tuesday morning, the day before his summit is scheduled there with Trump.

Kim left his train at Dong Dang, a Vietnamese town by the Chinese border, early Tuesday morning and traveled the last 105 miles or so to Hanoi by car.

—ABS-CBN News Channel (@ANCALERTS) February 26, 2019

According to INSIDER's calculations, the trip spanned at least 2,000 miles.

Read more: PHOTOS: North Korean leader Kim Jong Un arrives in Vietnam ahead of second nuclear summit with Trump

A map roughly outlining Kim's train journey from Pyongyang to Hanoi via China on his way to his summit with Trump. Google Maps/INSIDER

Tracing Kim's steps

Kim crossed into Dandong, a Chinese city bordering North Korea, late Saturday, The Associated Press reported. The trip took him through southeastern China before eventually arrived in Vietnam.

He passed by the southeastern Chinese city of Hengyang around Monday afternoon local time, South Korea's Yonhap news agency reported.

Footage Japan's TBS news channel showed Kim taking a cigarette break as the train took a quick stop in Nanning, southern China, before dawn on Tuesday. His sister, Kim Yo Jong, can be seen carrying a crystal ash tray for him.

Read more: Inside Kim Jong Un's personal train — which is bulletproof, has all-white conference rooms, and its own red carpet ramp

'Traveling by train is a forced choice'

While Kim's laborious, three-day train ride undoubtedly gave him a good look at China's cities and countryside, experts say his reason for the journey more likely has to do with pride than with tourism.

Last year, Kim borrowed a Boeing 747 plane from Air China, the airline majority-owned by the Chinese state, to get himself to Singapore in June for his first summit with Trump.

His 40-year-old, Soviet-made Ilyushin Il-62 plane was deemed unsafe for the voyage at the time.

Kim exiting an Air China plane upon arrival at Changi Airport in Singapore for his summit with Trump in June. Ministry of Communications and Information of Singapore via AP

Kim's use of a Chinese plane last year highlighted his apparent reliance on Beijing, which didn't have any delegates at Singapore but saw its global vision dominant at the summit.

The North Korean leader did not appreciate remarks about his reliance on China last year, Cheng Xiaohe, a North Korea expert at Beijing's Renmin University, told The New York Times.

Kim's armored train in Beijing last March. Jason Lee

"He does not want to show the world his heavy reliance on China by waving his hand in front of China's national flag on a Chinese plane as he did at the Singapore airport," Cheng told The Times.

"Traveling by train is a forced choice."

It's not clear what mode of transport Kim will take home.

Read more: Kim Jong Un rode his personal armored train to China to spend his 35th birthday with Xi Jinping

A banner in a South Korean restaurant in Hanoi welcoming Kim and Trump to Vietnam. The two leaders are expected to meet on Wednesday and Thursday. Reuters/Kham

Trump has characterized the coming summit as a follow-up to the leaders' meeting in June, when Kim made a vague pledge to work toward denuclearization. Pyongyang appears not to have made much progress on that front.

US intelligence and North Korea experts have warned that Pyongyang is unlikely to give up its nuclear arms. An intelligence report published last month reiterated the idea that the country's leaders view nuclear arms as "critical to regime survival."

Trump has repeatedly played down hopes for any new breakthroughs with North Korea, and he told the Governors' Ball on Sunday that he was "not pushing for speed" with North Korea's denuclearization.

"I'm not in a rush," he said. "I don't want to rush anybody. I just don't want testing. As long as there's no testing, we're happy."

He added that US sanctions on North Korea would remain for the time being. Beijing for months has been urging the United Nations to relax some of its sanctions on North Korea.

Editor's note: An earlier version of this post suggested the train ride would last three-and-a-half days, rather than the two-and-a-half it ultimately took.