North Korean leader Kim Jong Un plans to travel to Russia this month to meet President Vladimir Putin and discuss supplying Moscow with weapons for the war in Ukraine, the New York Times reported.

In a rare trip abroad, Kim would travel from Pyongyang, probably by armoured train, to Vladivostok, on the Pacific Coast of Russia, where he would meet Putin, the Times reported on Monday, citing U.S. and allied sources.

White House national security spokesman John Kirby said on August 30 that the United States was concerned that arms negotiations between the two countries were advancing.

While in Vladivostok, a port city not far from North Korea, the two leaders would discuss Kim’s sending Russia artillery shells and anti-tank missiles in exchange for Moscow’s advanced technology for satellites and nuclear-powered submarines, the newspaper reported.