With Putin and Kim Jong Un set to meet, the West fears what Russia ...

Russian President Vladimir Putin, right, and North Korea's leader Kim Jong Un shake hands during their meeting in Vladivostok, Russia, Thursday, April 25, 2019.

Alexander Zemlianichenko | Pool | AP

The leaders of North Korea and Russia are scheduled to meet this week, with deepening military, economic and geopolitical cooperation on the official agenda.

Behind closed doors, however, White House officials and political analysts believe the talks between North Korean leader Kim Jong Un and Russian President Vladimir Putin will focus on arms deals and military cooperation that could potentially take their relationship to another, more disconcerting, level.

Ahead of Kim's arrival in Vladivostok in the early hours of Tuesday morning, the Pentagon said it had no detail on where exactly, or when, Putin and Kim's meeting would take place.

"As far as the details of that meeting and what will be discussed and when and where, I just don't have any information to provide," Pentagon Press Secretary Brig. Gen. Pat Ryder said Monday.

"I would just again reiterate that we remain concerned that North Korea is contemplating providing any type of ammunition or materiel support to Russia, in support of their war against Ukraine."

There are concerns that Pyongyang could provide weaponry to Russia for use in its war in Ukraine, including millions of artillery shells, rockets, anti-tank missiles and small arms ammunition. There are also fears about what Moscow might offer the economically isolated and heavily sanctioned North Korea in return.

A fire assault drill by North Korean rocket artillery units at an undisclosed location in North Korea in March 2023 in this photo released by North Korea's Korean Central News Agency (KCNA). Around 6,000 of these units are located in range of South Korean population centers.

KCNA | Reuters

The White House said on Monday that any arms deal or military support for Russia's war in Ukraine would directly violate a number of UN Security Council resolutions and added that it's ready to impose more sanctions against North Korea without hesitation.

Any deal between the two powers is expected to go beyond weaponry, with experts noting that this burgeoning "transactional" relationship could see advanced military technology and intelligence shared with Pyongyang — which could enable it to further that nuclear program and weapons of mass destruction.

North Korea has had numerous sanctions imposed on it due to its prohibited development and testing of missiles and nuclear weapons in recent years. That Russia could potentially share such information with a so-called "rogue state" like North Korea — and behave similarly itself as it threatens global peace and security — should worry the West, experts say.

"We should not be unconcerned" by this meeting, Edward Howell, lecturer in Politics at Oxford University and an expert on North Korea's domestic and foreign policy, told CNBC.

"Pyongyang's rapprochement with Moscow could mean that a transactional network of information exchange — in addition to weapons and technological exchange — continues, including other rogue state actors, too," he said Monday.

"We must remember that in the past, North Korea has actively engaged in the clandestine proliferation of nuclear weapons-related technology and fissile material with Pakistan, Syria, and Libya." 

North Korean leader Kim Jong Un and his daughter Kim Ju Ae watch a missile drill at an undisclosed location in this image released by North Korea's Central News Agency (KCNA) on March 20, 2023. 

Kcna | Reuters

Moreover, Howell said, such actions by Russia and North Korea would make it harder for international institutions to encourage re-compliance with the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) from which North Korea withdrew in 2003.

"If the UN Security Council becomes unable to dampen Pyongyang's nuclear ambitions, then the likelihood of North Korea getting away scot-free with a seventh nuclear test in the future becomes ever-higher," he added.

CNBC has contacted the Kremlin and North Korea's embassy in London for comment and further details on the talks and is awaiting a reply.

For their part, Russia and North Korea have both denied claims of alleged arms dealing.

Kremlin Press Secretary Dmitry Peskov told reporters Tuesday morning that the talks would focus on "issues of bilateral cooperation," as well as "sensitive areas," without providing further detail.

North Korean state media said Kim attended the missile launch with both his wife and "beloved daughter"

STR / AFP - Getty Images 

Asked to comment on the White House's warning to North Korea about the potential sale of weapons to Russia, Peskov said Moscow and Pyongyang were not interested in statements from the U.S.

"The interests of our two countries are important for us, and not warnings from Washington. It is the interests of our two countries that we will focus on," he said, adding that Russia was also ready to discuss "issues related to the sanctions of the UN Security Council," without giving further details.

Kim's visit to Vladivostok, where the Eastern Economic Forum is taking place this week, is an unusual one for the reclusive and despotic leader. It's only his second visit to ally Russia and he is not believed to have left North Korea since the Covid-19 pandemic.

Kim's trip to Vladivostok, which lies around 80 miles from the North Korean border, was made on his armored train, South Korean media reported.

White House officials warned that arms negotiations between the countries were "actively advancing" ahead of the meeting; North Korea and Moscow denied the claims.

Western allies — and particularly Japan and South Korea that deal with North Korea's saber-rattling and unpredictability regularly, not to mention its nuclear and missile tests — say they're monitoring the Kim/Putin summit closely.

"We are watching the situation with concern, including the possibility that it could lead to a violation of the relevant UN Security Council resolutions that prohibit all procurement of weapons and related materials from North Korea, as well as the possible impact on Russia's aggression in Ukraine," Japan's government spokesman noted in a press briefing Tuesday.

North Korea's attempt to put a spy satellite into orbit ended in failure, state media said on August 24, 2023 just months after Pyongyang's first launch crashed into the ocean shortly after blast off.

Jung Yeon-je | AFP | Getty Images

Describing the Kim-Putin summit as "just the tip of a dangerous iceberg," Teneo Intelligence advisors Victor Cha and Andrius Tursa noted that "ties between the two seemed to accelerate quickly in the past two months" with Defense Minister Sergei Shoigu's recent visit to Pyongyang.

"Near-term, one major concern is whether Russian cooperation will extend to supplying new ballistic missile technology to North Korea, something the Kim regime desires even above food imports for its citizens," the analysts said in a research note last week.

"The trajectory of this cooperation suggests that Moscow could continue to help Pyongyang enhance its missile arsenal," they said, adding that an immediate concern is whether Russia will supply missile technologies in return for more North Korean weapons longer term.

Any "aggressive military posturing could ignite a crisis on the Korean peninsula," they added, and make "life difficult for the U.S. and its partners, who have few efficacious tools with which to respond to the emerging axis."

In late August, U.S. National Security Council spokesman John Kirby said the U.S. had evidence that North Korea had provided rockets and artillery to the Russian mercenary group Wagner "months ago," adding that Moscow had continued to canvas for more munitions.

Russian President Vladimir Putin grimaces while visiting the Zvezda Shipbuilding Complex on September 11, 2023, in Bolshoi Kamen, outside of Vladivostok, Russia.

Getty Images

"We urge the DPRK [Democratic People's Republic of Korea] to cease its arms negotiations with Russia and abide by the public commitments that Pyongyang has made to not provide or sell arms production," Kirby said. "And of course, we'll take action directly by exposing and sanctioning individuals and entities working to facilitate arms deals between these two countries."

He noted, however, that as yet, the U.S. has not seen Pyongyang provide weapons directly to Moscow.

"We will see how it goes," Kirby said, adding that the U.S. does not have formal diplomatic relations with North Korea and therefore will continue to issue warnings publicly.