She is Kim Jong-un’s closest confidante – a trusted member of the North Korean ruling dynasty who has shadowed her elder brother during every step of his transformation from nuclear pariah to statesman.

As Kim made the long train journey from Pyongyang to Hanoi for his second denuclearisation summit with Donald Trump, Kim Yo-jong was by his side again – this time with an ashtray.

Footage captured by the Japanese TV network TBS shows Kim Jong-un, a heavy smoker, taking a pre-dawn cigarette break on Tuesday at Nanning railway station in southern China during his 70-hour journey to Vietnam for his two-day meeting with the US president.

Chad O'Carroll (@chadocl) Kim Jong Un had a cigarette break this morning at Nanning station in China.



Kim Yo Jong can be seen carrying an ashtray for him.



Hyon Song Wol also visible in one shot.



Pics from TBS Japanhttps://t.co/3imj1VnugQ pic.twitter.com/gu3cATjjiK

His craving apparently satisfied, he walks towards his sister, who is holding out what appears to be a crystal ashtray into which he places his cigarette butt.

Also seen on the platform is Hyon Song-wol, a member of North Korea’s ruling party elite and the leader of the famous Moranbong girl band handpicked by Kim. Hyon’s inclusion in Kim’s delegation has raised speculation that cultural events could be part of the agreements reached between Washington and Pyongyang this week as they look for easier steps to improve relations.

Official photographs often show Kim with a cigarette dangling between his fingers, even on a visit to an orphanage and, in July 2017, while standing next to a liquid-fuel intercontinental ballistic missile shortly before its test launch.

But he was forced to go without during his first meeting with the South Korean president, Moon Jae-in, just south of their countries’ heavily armed border last April. Over the course of their meetings, Kim did not light up once in Moon’s presence, apparently out of respect for his South Korean counterpart, who is 31 years his senior.

Reports said Kim succumbed just once, quietly slipping out of the crowded banquet hall in the evening to smoke in a separate room.

Kim Yo-jong, who holds senior positions in the Workers’ party of Korea, has been a visible presence throughout the high-stakes diplomatic process that will continue in Hanoi from Wednesday.

She represented Kim at the start of last year’s Pyeongchang Winter Olympics in South Korea and was present at the second inter-Korean summit last May.

And when Kim and Trump agreed to work towards the denuclearisation of the Korean peninsula during their first meeting in Singapore last June, the North Korean leader insisted on signing the joint statements with his own pen, handed to him – cap removed – by his sister.