Russian President Vladimir Putin (R) shakes hands with top leader of the Democratic People's Republic of Korea (DPRK) Kim Jong Un in Vladivostok, Russia, April 25, 2019. (Xinhua/Sputnik)

VLADIVOSTOK, Russia, April 25 (Xinhua) -- Russian President Vladimir Putin and top leader of the Democratic People's Republic of Korea (DPRK) Kim Jong Un on Thursday said that they had substantial discussions on bilateral ties and the Korean Peninsula nuclear issue during their first-ever meeting.

The four-hour talks started with a one-on-one conversation between the two leaders and they were later joined by members of national delegations.

The two sides had an in-depth discussion on various topics including the denuclearization of the Korean Peninsula, bilateral relations, the United Nations and relations with the United States.

Putin reaffirmed that "there is no alternative to the peaceful solution of nuclear and other issues on the Korean Peninsula," adding that Russia is ready to continue cooperation to reduce tensions on the peninsula, and to strengthen security in Northeast Asia as a whole.

"Denuclearization means to a certain extent the disarmament of the DPRK. Definitely, the DPRK needs guarantees of its security and the preservation of sovereignty," Putin said at a press conference after talks with Kim.

For his part, Kim said that he and Putin had a fruitful discussion on "ways of peaceful settlement" of the Korean Peninsula nuclear issue, which has become one of the most pressing issues on the international agenda.

"I hope that our negotiations will continue along the same lines in a useful and constructive way," Kim said.

On bilateral cooperation, Putin said that they had discussed a number of potential joint projects, such as a railway linking Russia with the Korean Peninsula, a pipeline for transportation of oil and gas, as well as electricity networks.

He underlined all of the projects are possible and are "in the interests of South Korea."

"In my opinion, if these projects and others like them were implemented, this would create the necessary conditions for increasing the trust necessary to solve the essential problems," Putin said.

Kim arrived here on Wednesday for his first meeting with Putin, which came at a time when tensions are growing between the DPRK and the United States.

The DPRK top leader has met U.S. President Donald Trump twice. Their second summit ended in Vietnam's Hanoi on Feb. 28 without an agreement.

After the failure of the Trump-Kim meeting in Hanoi, "now it is necessary to give the entire settlement process some kind of impulse and push it forward," former Russian Ambassador to South Korea Gleb Ivashentsov said.

He said that the Putin-Kim meeting provides such an impetus for the political settlement on the Korean Peninsula issue, noting that Russia is beginning to act as a more active participant in the process.

"Pyongyang needs conciliatory gestures," Ivashentsov said.

In addition, Ivashentsov noted the importance of Russia-China cooperation on this matter, saying that "perhaps further we will discuss some broader negotiations."