Russian President Vladimir Putin said after holding his first face-to-face talks with North Korean leader Kim Jong Un that US security guarantees would probably not be enough to persuade Pyongyang to shut its nuclear programme.

Putin and Kim held a day of talks on an island off the Russian Pacific city of Vladivostok two months after Kim's summit with US President Donald Trump ended in disagreement, cooling hopes of a breakthrough in the decades-old nuclear row.

The talks between Putin and Kim did not appear to have yielded any major breakthrough.

But Putin, keen to use the summit to burnish Russia's diplomatic credentials as a global player, said he believed any US guarantees might need to be supported by the other nations involved in previous six-way talks on the nuclear issue.

That would mean including Russia, China, Japan and South Korea as well as the United States and North Korea, a long-standing format that has been sidelined by unilateral US efforts to broker a deal.

"They (the North Koreans) only need guarantees about their security. That's it. All of us together need to think about this," Putin told reporters after talks with Kim.

"...I'm deeply convinced that if we get to a situation when some kind of security guarantees are needed from one party, in this case for North Korea, that it won't be possible to get by without international guarantees. It's unlikely that any agreements between two countries will be enough."

Such guarantees would have to be international, legally-binding, and vouch for North Korea's sovereignty, said Putin.

The two leaders appeared to get on well. The first session between Putin and Kim, comprising one-on-one talks with just a few aides present, lasted twice as long as the 50 minutes allocated in the schedule.

Putin described Kim as "quite open" and as "thoughtful" and "interesting".

Promising to brief the Chinese and US leadership about his talks, Putin said he thought a deal on Pyongyang's nuclear programme was possible and that the way to get there was to move forward step-by-step in order to build trust.

Kim, who arrived in Vladivostok on Wednesday on board his armoured train, said the situation on the Korean peninsula "is an issue that the world is very interested in".

Before the Putin-Kim meet, US Secretary of State Mike Pompeo said on Wednesday he expected "bumpy" talks ahead with North Korea but that he still hoped to reach a potentially landmark denuclearization deal.

In an interview with CBS News, Pompeo said the Hanoi summit had more "nuance" than publicly reported, with the two sides sharing their positions.

North Korea has demanded an easing of sanctions and Trump has indicated sympathy, saying he is fond of Kim.