HANOI (REUTERS) - When North Korean leader Kim Jong Un rolled into the Vietnamese border station of Dong Dang early on Tuesday (Feb 26), his vaunted specialised train was pulled by a red-and-yellow locomotive emblazoned with China's national railway logo.
It was the second time Mr Kim had arrived for a summit with US President Donald Trump in transport provided by the Chinese, underscoring just how much the young leader's sudden flurry of international engagements has depended on his larger, more powerful neighbour.
When Mr Kim arrived in Singapore last year for his first historic summit with Mr Trump, it was in an Air China jumbo jet bearing the Chinese flag.
With the exception of two summits with South Korean President Moon Jae-in on the border between the two Koreas, every one of Mr Kim's unprecedented summits with China's President Xi Jinping and now the second summit with Mr Trump depended on trains provided by the Chinese.
"This is a full service from Xi," said Mr Nam Sung-wook, a former South Korean intelligence official. "Kim couldn't travel without China's special treatment."
To travel to his four summits with Mr Xi, the North Korean leader's specially equipped string of train carriages was usually hauled by matching green DF11Z locomotives, Chinese-made engines sporting the emblem of the state-owned China Railway Corporation, with at least three different serial registration numbers, according to a review of media images.
At the time of his first trip to Beijing in March 2018, South Korean media reported that the locomotives were usually used for carrying top Chinese officials, and were connected to Mr Kim's carriages in the city of Dandong, on the Chinese side of its border with North Korea.
The red-and-yellow DF4 engine used when Mr Kim arrived in Vietnam was of a different, older type than the more typical green DF11Z spotted by media pulling the train when it entered China from North Korea on Saturday.
It's not clear when China provided the train engines to North Korea, or under what conditions.
Asked about the apparent change in locomotives and whether China had provided them, Chinese Foreign Ministry spokesman Lu Kang said he had not paid much attention to the issue. "I don't know whether changing the train has any particular meaning towards your appraisal of the situation," he told a daily news briefing on Tuesday.
China, however, provided a "transport guarantee" for Mr Kim's train travel, Mr Lu said without elaborating, likely referring to ensuring that Mr Kim's train was able to proceed smoothly across China.
SLOW TRAIN THROUGH CHINA
Mr Kim's slow journey from North Korea across thousands of kilometres in China to Vietnam is the longest he has taken as leader, with state media running photos of schoolchildren studying globes and asking: "Where is the Dear Leader now?"
Media outlets captured rare images of Mr Kim in a private moment, smoking a cigarette during a break on a station platform in China.
His train is believed to be armoured, and state media images have shown an interior decked out with pink leather chairs and big-screen televisions.
That wasn't enough to impress some Chinese Internet users who took to social media to crack jokes about the relative poverty and backwardness of their awkward neighbour, the diesel locomotive lent to Mr Kim a stark contrast to the network of high-speed trains in China.
"Travelling like this from Pyongyang to Hanoi?" wrote one user on China's Weibo social media platform, above a picture of an old steam train.
"Under sanctions by the Americans for 50 years and poverty-struck North Korea can't even afford to buy a plane," wrote another Weibo user.
A third complained of a brief period of gridlock around the railway lines in the north-eastern Chinese city of Jinzhou as police shut off roads, likely to ensure security as Mr Kim's train passed through.
Mr Kim Han-tae, a South Korean former train engineer who published a book last year on North Korea's railways, said the Chinese had put in a lot of work to facilitate Mr Kim's trip.
The decision to have the North Korean carriages hauled by Chinese engines was likely a logistical one, he said.
"The bottom line is when the train comes from North Korea via China, it has to be run by Chinese to get it to operate on China's rail system and of course the engine car has to be Chinese," he said.
One of the DF11Z engines used when the North Korean leader travelled to Beijing in January is seen in a photograph on a rail-spotting website from June 2017 pulling a double-decker passenger train in Beijing.
Images on North Korean state media, meanwhile, have shown Mr Kim arriving with different engines from those spotted in Beijing, suggesting the DF111Z trains now associated with his trips are only used in China.