Tensions between Pyongyang and Washington have continued to simmer in the wake of the two summits, with North Korea recently calling for the replacement of US Secretary of State Mike Pompeo as a negotiator.
Still, as evidenced by the mild tone, it shows the North is still reining in any harsh rhetoric toward the US and directly criticizing President Donald Trump as it seeks to keep the talks alive.
Ushakov met last week in Moscow with Fiona Hill, a foreign policy adviser to Trump, for talks on North Korea.
Since Hanoi, the North has not attended any of the eight regular weekly meetings of the heads of their joint liaison office in Kaesong, and has not taken part in other joint projects, such as excavations in the DMZ.
The Kremlin said in a brief statement last week that Kim will visit Russian Federation "in the second half of April", but gave no further details.
Biegun urged Moscow to maintain sanctions against the isolated country to fulfill a shared goal of advancing the denuclearization discussion.
The summit may be held at Vladivostok's Far Eastern Federal University, media reports say.
Local media have reported preparations and strict security measures undertaken in Vladivostok where the Korean leader is expected to arrive by train.
However, Japan now finds itself battling to keep itself relevant in the fast-moving North Korea issue as Kim expands his diplomatic circle.
"It's not that Kim is some great friend with Russian Federation".
He added that Russia's trade with North Korea is minuscule at just $34 million past year, mostly because of the global sanctions against Pyongyang. "It's part of his plan to continue work on diplomacy with everybody else, to put pressure on Washington", said Sue Mi Terry, senior fellow at the Center for Strategic and International Studies in Washington.
Earlier on Tuesday, North Korea confirmed the meeting in a terse, two-sentence statement.
"Kim Jong-un will remain in Vladivostok to see the sights and the places his father Kim Jong-il visited in 2002", the agency alleged.
"The president is fully prepared to have a third summit if he can get a real deal", Bolton said in the interview. "Because at the end of the day this is a meeting at the summit level with a world leader", said John Park, director of the Korea Project at the Harvard Kennedy School. When Kim meets with Putin for their first one-on-one meeting, he will have a long wish list and a strong desire to notch a win after the failure of his second summit with U.S. President Donald Trump in February 2019.
Denyer reported from Seoul.