WASHINGTON >> Kim Jong Un, the leader of North Korea, plans to travel to Russia this month to meet with President Vladimir 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, Kim would travel from Pyongyang, North Korea’s capital, probably by armored train, to Vladivostok, on the east coast of Russia, where he would meet with Putin, the officials said. Kim could possibly go to Moscow, though that is not certain.

Putin wants Kim to agree to send Russia artillery shells and anti-tank missiles, and Kim would like Russia to provide North Korea with advanced technology for satellites and nuclear-powered submarines, the officials said. 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 Sunday to Sept. 13, according to the officials. North Korea celebrates the anniversary of its founding on Saturday.

On Wednesday, the White House warned that Putin and Kim had exchanged letters discussing a possible arms deal, citing declassified intelligence. A White House spokesperson, John F. Kirby, said high-level talks on military cooperation between the two nations were “actively advancing.”

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 spokesperson, 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 DPRK 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.

This article originally appeared in The New York Times.