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. Kim could possibly go to Moscow, though that is not certain.

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.