North Korea’s Kim Jong Un was in Russia on a rare overseas visit Tuesday ahead of a meeting with President Vladimir Putin, sparking warnings from Washington over a possible arms deal for Moscow’s war in Ukraine.

Wearing a black suit and flanked by uniformed defence officials, North Korean state media images showed an unsmiling Kim waving from the doorway of his heavily-armoured private train with green-and-gold livery as it departed Pyongyang station.

Russian state news agency, Ria Novosti, confirmed Kim’s train had crossed the border into the Primorsky region, with images showing a train with dark green carriages being pulled along a track by a Russian Railways locomotive.

Kim will meet Putin in the Far East later this week, Kremlin spokesman Dmitry Peskov said according to Ria Novosti.

It is possible the pair will meet on the sidelines of the Eastern Economic Forum in Vladivostok, the Far East city closest to the North Korea-Russia border..

KIM is accompanied by top North Korean military officials, including officials in charge of weapons production and space technology,