Here’s Why Kim Jong Un May Have Opted for an Arduous Train Journey to Reach Vietnam

Instead of taking a short flight to Vietnam’s capital, North Korean leader Kim Jong Un rattled through China on his armored train, journeying south from Pyongyang over 2,000 miles to meet President Donald Trump for their second nuclear summit. This was no high-speed rail.

On Tuesday, after a reported 60-hour, or two-and-half day trip, the 35-year-old leader of the world’s most secretive hermit kingdom alighted at the railway station in Dong Dang, Vietnam. Kim was then picked up by a limo, and driven the rest of the way to Hanoi, according to the Associated Press.

This seeming anachronistic mode of travel has long been favored by the Supreme Leaders, Kim, his father and his grandfather. The distinctive green and yellow train adds to the shroud of mystery cloaking North Korea, and is part of the Kim dynasty’s lore.

Here are the possible reasons behind Kim’s unusual form of transit.

Riding a train is the family tradition

Kim’s father, Kim Jong Il, and his grandfather, Kim Il Sung, were both allegedly afraid of flying. South Korean media has speculated that the fear was triggered when the two witnessed the explosion of their jet during a test flight. The incident happened in 1982. While Kim Il Sung flew to the Soviet Union after, in 1986, it was the last time a North Korean leader publicly traveled abroad by air for more than three decades, according to AP.

By contrast, Kim Jong Un is believed to have become a frequent flier during his boarding school days in Switzerland. Since taking office in 2011, he has also occasionally opted to fly, including to Singapore last year for his first tete-a-tete with Trump. But his preference for rails this trip could be an ode to his family line and a way to keep up the train travel tradition among North Korean leaders.

Kim’s armored train provides more security—and luxury—than a flight

Kim’s train, the same one used by his father and grandfather, has 21 bulletproof carriages with plush leather sofas and conference rooms, according to Reuters.

Chosun Media states that two separate trains travel with the main entourage; the one in front handles security checks to ensure the railway tracks are safe, and the one behind carries bodyguards and support personnel.

North Korea lacks the air infrastructure that would make a flight possible

Kim’s decision to take the 60-hour journey may have also been a matter of pride. To get to Singapore for the Trump summit last June, Kim borrowed a Boeing 747 Air China plane because his Soviet-made Ilyushin Il-62 aircraft was deemed unsafe, suggesting that without external help, a flight to Vietnam would not be possible. By opting for the train instead, Kim could show that he is not reliant on Beijing, analysts have suggested.

Kim is expected to commence his nuclear summit with U.S. President Donald Trump on Wednesday.