North Korean leader Kim Jong Un arrived in Russia Tuesday where he is expected to hold talks with Russian President Vladimir Putin in Russia’s far east amid warnings from the U.S. and South Korea against a potential arms transfer.

Tuesday, South Korean officials said they are closely monitoring the first meeting between Kim and Putin in four years.

“The Ministry of National Defense believes that Kim Jong-un probably entered Russia early this morning using a private train,” said spokesperson Jeon Ha-kyu, citing “the presence of a large number of military personnel” that accompany Kim.

“We are closely watching whether negotiations related to arms trade and technology transfer between North Korea and Russia will take place,” he added.

Kim and Putin reportedly will discuss North Korea supplying Russia with more weapons to be used in its war against Ukraine and other military operations, while Kim appears to be looking for Russia to give North Korea advanced technology for its satellites and nuclear-powered submarines, as well as food assistance.

In Moscow, Kremlin spokesman Dmitry Peskov said Tuesday that Kim’s visit to Russia will be “full-fledged.” “There will be negotiations between two delegations, and after that, if necessary, the leaders will continue their communication in a one-on-one format.”

The U.S. and South Korea have renewed warnings to North Korea not to provide munitions to Russia that could be used in the Ukraine war.

“No United Nations member country should violate the U.N. Security Council sanctions and resolutions, including [engaged in] illegal arms trade,” said South Korea’s foreign ministry spokesperson Lim Soo-suk during a Tuesday briefing.

In Washington, State Department said any transfer of arms from North Korea to Russia would be in violation of multiple United Nations Security Council resolutions.

“We of course have aggressively enforced our sanctions against entities that fund Russia’s war effort, and we will continue to enforce those sanctions and will not hesitate to impose new sanctions if appropriate,” according to State Department spokesperson Matthew Miller during a Monday briefing.

But some analysts are skeptical that weapons provided by North Korea to Russia could have substantial impact on Ukraine war.

“North Korean aid to Russia, as far as we know, is going to come in the form of small arms aid. It’s probably not going to be in the form of weapons of mass destruction, or any other sort of weaponry that’s going to necessarily turn the tide in Ukraine,” Honolulu-based Pacific Forum analyst Rob York told VOA on Tuesday.

Kim held his first summit meeting with Putin on April 25, 2019, at the Russian port city of Vladivostok.

Lee Juhyun contributed to this report.