Kim Jong-un, the leader of North Korea, plans to travel to Russia this month to meet with President Vladimir V. Putin to discuss the possibility of supplying Russia with more weaponry for its war in Ukraine and other military cooperation, according to American and allied officials.
In a rare foray from his country, Mr. Kim would travel from Pyongyang, North Korea’s capital, probably by armored train, to Vladivostok, on the Pacific Coast of Russia, where he would meet with Mr. Putin, the officials said.
Mr. Putin wants Mr. Kim to agree to send Russia artillery shells and antitank missiles, and Mr. Kim would like Russia to provide North Korea with advanced technology for satellites and nuclear-powered submarines, the officials said. Mr. Kim is also seeking food aid for his impoverished nation.
Both leaders would be on the campus of Far Eastern Federal University in Vladivostok to attend the Eastern Economic Forum, which is scheduled to run Sept. 10 to 13, according to the officials. Mr. Kim also plans to visit Pier 33, where naval ships from Russia’s Pacific fleet dock, they said. North Korea celebrates the anniversary of its founding on Sept. 9.
On Wednesday, the White House warned that Mr. Putin and Mr. Kim had exchanged letters discussing a possible arms deal, citing declassified intelligence. A White House spokesman, John F. Kirby, said high-level talks on military cooperation between the two nations were “actively advancing.” U.S. officials declined to give more details on the state of personal ties between the leaders, who are considered adversaries of the United States.
The new information about a planned meeting between them goes far beyond the previous warning. The intelligence relating to the plans has not been declassified or downgraded by the United States, and the officials describing it were not authorized to discuss it. They declined to provide details on how spy agencies had collected the information.
While the White House declined to discuss the new intelligence, Adrienne Watson, a National Security Council spokeswoman, acknowledged that the United States expected “leader-level diplomatic engagement” on the issue of arms sales to take place between Russia and North Korea, officially known as the Democratic People’s Republic of Korea.
“We urge the D.P.R.K. to cease its arms negotiations with Russia and abide by the public commitments that Pyongyang has made to not provide or sell arms to Russia,” she said in a statement after this story was published.
At other times since Russia began its full-scale invasion of Ukraine, U.S. officials have released declassified intelligence to try to dissuade North Korea, China and other countries from supplying Russia with weapons. U.S. officials say White House warnings about planned transfers of North Korean artillery shells stopped previous cooperation between Pyongyang and Moscow.
In late August, a delegation of about 20 North Korean officials, including some who oversee security protocols for the leadership, traveled by train from Pyongyang to Vladivostok, and then flew to Moscow, an indication that North Korea was serious about a visit by Mr. Kim. Their trip, believed to be a planning expedition, took about 10 days, according to officials briefed on the intelligence reports.
One potential stop for Mr. Kim after Vladivostok, an official said, is Vostochny Cosmodrome, a space launch center that was the site of a meeting in April 2022 between Mr. Putin and Alexander Lukashenko, the president of Belarus and a partner of Mr. Putin’s in the war in Ukraine. The center, whose first rocket launch took place in 2016, is about 950 miles north of Vladivostok. Another possible stop for Mr. Kim is Moscow, the official said.
The idea for the Russia visit came out of a trip by Sergei K. Shoigu, the Russian defense minister, to North Korea in July for Mr. Kim’s celebration of the 70th anniversary of the “victory” over South Korean and U.S. forces in the Korean War, officials said. (In reality, the three-year war halted in 1953 in a stalemate and armistice agreement, and the two Koreas are still officially at war.)
Mr. Kim took Mr. Shoigu to an exhibition of weaponry and military equipment that included ballistic missiles banned by the United Nations.
During the meeting, Mr. Kim presented Mr. Shoigu with options for greater military cooperation and asked for Mr. Putin to visit North Korea, officials said. Mr. Shoigu then made a counterproposal, suggesting that Mr. Kim travel to Russia.
Mr. Shoigu’s visit to North Korea was the first by a Russian defense minister since the fracturing of the Soviet Union in 1991. Mr. Shoigu presented Mr. Kim with a letter from Mr. Putin, according to the Korean Central News Agency, or KCNA, the country’s state news service.
The agency did not indicate that Mr. Kim had explicitly mentioned Ukraine in the conversations, but it said that he had “expressed his views on the issues of mutual concern in the struggle to safeguard the sovereignty, development and interests of the two countries from the highhanded and arbitrary practices of the imperialists and to realize international justice and peace.”
Mr. Putin has characterized his war against Ukraine as one of protecting Russian sovereignty, since in his view Ukraine should be part of a restored Russian Empire.
In June, Mr. Kim sent Mr. Putin a message on Russia’s national day in which he pledged to “hold hands” with the Russian leader and promised that the Russian people would have North Korea’s “full support and solidarity” for their “all-out struggle,” according to the KCNA.
“The strengthening of the Russia-North Korea alliance comes at an opportune time for two countries with very few allies and a shared adversary in the United States,” said Jean H. Lee, a recent senior fellow on the Koreas at the Wilson Center. “It’s the resurrection of a traditional alliance that serves the strategic interests of both Putin and Kim.”
A Chinese delegation led by Li Hongzhong, a member of the Politburo of the Chinese Communist Party, also visited North Korea for its celebration, and Mr. Li handed Mr. Kim a letter from Xi Jinping, China’s leader, according to North Korean state media.
Mr. Kim often exchanges affectionate and sometimes downright effusive letters with foreign leaders whom he considers allies or potential partners. He and President Donald J. Trump exchanged a series of letters as they prepared for historic face-to-face summits.
For the second of those summits, held in February 2019 in Hanoi, Vietnam, Mr. Kim traveled by armored train for two days from Pyongyang through China and across its tropical border with Vietnam. Mr. Kim’s father, Kim Jong-il, and his grandfather, Kim Il-sung, both preferred to travel by train outside the country.
Mr. Kim first visited Russia in 2019, when he arrived in Vladivostok on his armored green train to meet with Mr. Putin. As the train pulled slowly into the station, white-gloved North Korean attendants raced alongside it, frantically wiping down any handholds and other surfaces that Mr. Kim might touch as he disembarked.
A beaming Mr. Kim stepped off in a black fedora and long black coat. He was received by an honor guard and brass band. Mr. Kim’s bodyguards jogged next to the black limousine that carried him through the city.
The United States first warned about cooperation between North Korea and Russia a year ago. Officials, citing declassified U.S. intelligence, said that Russia planned to buy artillery shells for use in Ukraine.
In subsequent disclosures, Mr. Kirby said North Korea had shipped munitions to Russia through the Middle East and North Africa.
But U.S. officials said that the disclosures had deterred North Korea and that few if any North Korean weapons had made it to the front lines in Ukraine.
Deterring support for Russia from North Korea, Iran and China is a critical element of the Biden administration’s strategy for helping Ukraine in its defense against Russia.
China, warned by Secretary of State Antony J. Blinken in February not to provide lethal aid, has supplied dual-use technology and components but has not yet sent drones or heavy weaponry to the Russian military, U.S. officials said.
Iran has supplied drones and is helping Russia build a drone factory. But U.S. officials believe their warnings have helped prod Iran to reconsider plans of providing ballistic missiles to Russia, at least so far.