SEOUL, South Korea — North Korean leader Kim Jong Un left Russia on Sunday, Sept. 17, 2023, ending a six-day trip that triggered global concerns about weapons transfer deals between the two countries locked in separate standoffs with the West.

Kim’s armored train departed to the sound of the Russian patriotic march song “Farewell of Slavianka” at the end of a farewell ceremony at a railway station in Artyom, a far eastern Russian city about 200 kilometers from the border with North Korea, Russia’s state news agency RIA reported.

Senior officials including Russia’s Minister of Natural Resources Alexander Kozlov and Primorye regional Gov. Oleg Kozhemyako were present at the ceremony, which featured a Russian military band playing both North Korean and Russian national anthems.

It was Kim’s longest foreign travel since he took power in late 2011. Observers said Kim was expected to return to Pyongyang, the North Korean capital, around Monday afternoon.

Since entering Russia last Tuesday in his first overseas trip in more than four years, Kim had met President Vladimir Putin and visited key military and technology sites, underscoring the countries’ deepening defense cooperation in the face of separate, intensifying confrontations with the U.S. and its allies.

Foreign officials and experts have said North Korea could provide badly needed munitions for Moscow’s war on Ukraine in exchange for sophisticated Russian weapons technology that would advance Kim’s nuclear ambitions.

North Korea may have tens of millions of aging artillery shells and rockets based on Soviet designs that could bolster Russian forces in Ukraine, analysts say, even though its old artillery systems have a reputation for poor accuracy. Both sides have been reportedly firing thousands of artillery rounds a day.

U.N. Security Council resolutions — which Russia, a permanent member, previously endorsed — ban North Korea from exporting or importing any arms. Observers say Russia’s alleged attempts to receive ammunitions and artillery shells from North Korea suggest Moscow’s desperation to refill its arsenal exhausted in the war with Ukraine.

“Military cooperation between North Korea and Russia is illegal and unjust as it contravenes U.N. Security Council resolutions and various other international sanctions,” South Korean President Yoon Suk Yeol said in written responses Sunday to questions from The Associated Press. “The international community will unite more tightly in response to such a move.”

In return for supplying conventional arms to Russia, experts say North Korea would seek Russian economic and food aid but also transfers of technologies to build powerful missiles, a nuclear-propelled submarine and a spy satellite. North Korea has publicly sought to introduce such high-tech weapons systems citing what it called intensifying U.S.-led hostilities. / AP