Russian news agency Interfax also confirmed that Kim was in Russia, citing Kremlin spokesperson Dmitry Peskov.

The Kremlin said Monday that Kim was visiting at Putin’s invitation and that there would be negotiations between delegations from the two countries. It said that Kim’s visit would happen in “the coming days” and that it could include a one-on-one meeting with Putin “if necessary.”

North Korean state media reported Tuesday that Kim left for Russia from Pyongyang, the North Korean capital, by train Sunday afternoon. He was accompanied by unspecified officials from the military, the government and his ruling Workers’ Party of Korea, state news agency KCNA said.

Kim received “a warm send-off” from senior officials in Pyongyang, according to the agency, which did not say whether he had arrived in Russia. State media photos showed Kim walking past honor guards and waving from his green-and-yellow train.

KCNA had said earlier that Kim and Putin were set to meet, without providing details.

One place they could meet is the eastern Russian city of Vladivostok, nearly 430 miles northeast of Pyongyang, where Putin arrived Monday for Russia’s Eastern Economic Forum. The two leaders met in Vladivostok during Kim’s last visit to Russia in 2019.

The U.S. Defense Department said Monday that “some type of meeting” was expected between Putin and Kim, whose trip to Russia is his first outside North Korea after three years of pandemic isolation.

Defense Minister Sergei Shoigu will join the talks, the Kremlin said Tuesday.

“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,” a spokesperson, Brig. Gen. Pat Ryder, told reporters.

“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,” he added.

The White House has repeatedly warned North Korea against making any arms deal with Russia, which would violate multiple United Nations Security Council resolutions. National security adviser Jake Sullivan said last week that North Korea would “pay a price” in the international community if it were to provide Russia with weapons.

State Department spokesperson Matthew Miller said Monday that the Biden administration would monitor any Putin-Kim meeting closely. He said the U.S. would continue to enforce sanctions against entities that fund Russia’s war effort “and will not hesitate to impose new sanctions if appropriate.”

Russia has been casting about for international support as it struggles against a Ukrainian counteroffensive, turning to fellow U.S. adversaries, including North Korea. Last month Kim and Putin exchanged letters pledging to increase their cooperation, according to U.S. officials and state media in both countries.

U.S. officials said last week that they expected Kim to travel to Russia and that arms talks were “actively advancing” and were likely to continue during Kim’s visit.

Experts say Russia would probably seek artillery munitions in exchange for providing energy and food aid to North Korea, where there are reports of starvation as Kim prioritizes his nuclear weapons and ballistic missile programs.

Kim may also want Russian assistance in advancing North Korea’s submarine, ballistic and satellite technologies, said Leif-Eric Easley, a professor at Ewha University in Seoul, South Korea.

But Russia is unlikely to make such technology transfers, he said, “because even a desperate war machine does not trade its military crown jewels for old, dumb munitions.”

He said the two countries would also avoid publicizing the full details of any arms deal “because of the serious international legal violations involved.”