(Reuters) - 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 Aug. 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.

At a time when the United States has expressed concern about growing military ties between the two countries, the news of Kim's planned visit came after Russia said it was discussing holding joint military exercises with North Korea.

"Why not, these are our neighbours. There's an old Russian saying: you don't choose your neighbours and it's better to live with your neighbours in peace and harmony," Interfax news agency quoted Russia's Defence Minister, Sergei Shoigu, as saying on Monday.

When asked about the possibility of joint exercises between the two countries, he said "of course" they were being discussed, it said.

South Korean news agency Yonhap earlier cited South Korea's intelligence agency as saying Shoigu, who visited Pyongyang in July, had proposed to Kim that their countries hold a naval exercise, along with China.