North Korea’s Kim Jong Un reportedly arrived in Russia Tuesday ahead of an expected meeting with President Vladimir Putin, officials said. The two leaders, flanked by their top military officials, are set to negotiate a potential arms deal to help resupply Moscow’s military drained by its war in Ukraine. North Korea may have tens of millions of artillery shells and rockets that could give a boost to the Russian army, analysts say. North Korea’s official Korean Central News Agency previously said Kim boarded his personal train Sunday afternoon en route to Russia, accompanied by unspecified members of the country’s ruling party, government and military. Jeon Ha Gyu, spokesperson of South Korea’s Defense Ministry, said South Korea’s military confirmed the train crossed into Russia sometime early Tuesday morning. SOUTH KOREA TALKS DOWN NORTH’S 1ST NUCLEAR SUBMARINE LAUNCH: ‘DECEPTION OR EXAGGERATION’ South Korean officials have been unable to identify Kim’s delegation, although it likely includes his foreign minister, Choe Sun Hui, and his top two military officials – Korean People’s Army Marshals Ri Pyong Chol and Pak Jong Chon. Other officials identified in North Korean state media photos include Pak Thae Song, chairman of North Korea’s space science and technology committee, and Navy Adm. Kim Myong Sik, who have both been a part of North Korea’s efforts to acquire spy satellites and nuclear-capable ballistic missile submarines. Experts have said North Korea requires external help to achieve these technologies, although it’s not clear if Russia would be willing to share. US THREATENS NORTH KOREA OVER RUSSIA ARMS DEAL, SAYS COUNTRY WILL ‘PAY A PRICE’ Kim Jong Un is also apparently bringing Jo Chun Ryong, a ruling party official in charge of munitions policies who also joined the dictator on recent tours to factories producing artillery shells and missiles, according to South Korea’s Unification Ministry, which analyzed the North Korean photos. PUTIN AND KIM JONG UN TO MEET IN RUSSIA IN DEFIANT MESSAGE TO WEST Putin was last seen in the eastern Russian city of Vladivostok, where he attended an international forum on Monday, according to Russia’s TASS news agency. Kremlin spokesperson Dmitry Peskov has said Putin and Kim will meet after the Vladivostok forum, which ends Wednesday, but did not specify when or where. U.S. officials are monitoring the international meeting between the heavily sanctioned countries and have vowed additional sanctions, should the meeting produce an arms agreement in violation of international security resolutions. “Arms discussions between Russia and the DPRK are expected to continue during Kim Jong Un’s trip to Russia,” said White House National Security Council spokesperson Adrienne Watson, referencing North Korea’s official name. “We urge the DPRK to abide by the public commitments that Pyongyang has made to not provide or sell arms to Russia.” State Department spokesman Matthew Miller added: “Any transfer of arms from North Korea to Russia would be a violation of multiple U.N. Security Council resolutions,” and the U.S. “will not hesitate to impose new sanctions.” Putin’s first meeting with Kim in 2019 was held in Vladivostok. The city is about 425 miles north of Pyongyang. The Associated Press contributed to this report.