WASHINGTON (NEXSTAR) — U.S. officials are watching with concern as North Korean leader Kim Jong Un meets with Russian President Vladimir Putin. 

The visit is shrouded in secrecy, but U.S. leaders say Russia may want North Korea to provide them with weapons for the war with Ukraine. 

Kim Jong Un arrived in Russia on Tuesday riding aboard a heavily-armored train. 

As Russia fights to gain ground in its war with Ukraine, its running low on ammunition. George Washington University National Security expert Thom Shanker says while North Korea is one of the poorest nations in the world, it’s also one of the most militarized. 

“Putin is looking to Kim, the North Korean leader for weapons,” Shanker said. “They have a huge supply of artillery shells for any potential war with South Korea and the U.S. and one can see Kim trading those to Putin.”

North Korea’s Kim Jong Un rolled into Russia on an armored train to see President Vladimir Putin. (Russian Ministry of Natural Resources and Ecology telegram channel via AP)

Experts worry North Korea may provide Russia with military supplies in exchange for economic help.  The State Department is keeping a close eye on that possibility. 

“It would be a sign of the desperate state in which the Russian government finds itself a year and a half into this war that it has been prosecuting unsuccessfully against Ukraine,” State Department spokesperson Matthew Miller said. 

Miller says any arms transfers between the countries would violate international agreements and warns there would be consequences. 

“We will monitor what happens and will not hesitate to take action to hold those accountable, if necessary,” Miller said. 

Those threats may not make a difference. 

“North Korea is one of the most sanctioned countries in the world so its hard to imagine what worse could be done,” Shanker said. 

Experts say as the U.S. pours more aid into Ukraine, North Korea re-supplying Russia will likely prolong the war. 

“As both sides rearm and get new weapons yes it means the fighting, the death, destruction, the injury will go on for even longer,” Shanker said.