North Korean leader Kim Jong Un will visit Russia within days, both countries confirmed Monday, with the two leaders expected to discuss a potential arms deal amid Moscow's deepening isolation over the war in Ukraine.

The Kremlin said in a brief statement that Kim would pay an official visit to Russia "in the coming days" at the invitation of President Vladimir Putin. The North's official Korean Central News Agency said that Kim would visit "soon" to "meet and have a talk with Comrade Putin."

Neither side offered a clear date for the meeting, but South Korean media, quoting government sources in Seoul, reported earlier Monday that Kim's personal armored train appeared to have left Pyongyang bound for the Pacific coast city of Vladivostok.

South Korean broadcaster YTN said that the summit could be held Tuesday or Wednesday, citing unnamed top government sources in Seoul.

The United States said last week that Kim was expected to visit Russia for talks with Putin to discuss an arms deal as the war in Ukraine burns through Moscow’s weapons stocks.

Kim's rare trip abroad — his first in four years — could see him meet with Putin as the Russian leader attends the Eastern Economic Forum, which kicked off Sunday and runs through Wednesday.

Kim's last trip outside the Korean Peninsula in 2019 was also for a meeting with Putin in Vladivostok.

Any agreement between the two pariah states to send much-needed artillery shells and antitank weapons to Moscow in exchange for food and advanced military technology for Pyongyang would help fortify the Russian military position amid a counteroffensive by Ukraine, while also giving North Korea more options to offset China's growing influence over it.

The United States has said it would be a "huge mistake" for North Korea to supply Russia with weapons to use in Ukraine and warned Pyongyang that it would "pay a price" if it followed through on a deal.

U.S. deputy national security adviser Jon Finer said Sunday that buying weapons from Pyongyang “may be the best and may be the only option” left for Moscow as it hopes to continue a war of attrition in Ukraine.

“It is interesting to reflect for a minute on what it says that when Russia goes around the world looking for partners that can help it, it lands on North Korea as maybe the best and maybe the only option that it's got, with maybe one or two exceptions,” Finer said.

Ties between Russia and North Korea have grown in recent years, with Russian Defense Minister Sergei Shoigu visiting Pyongyang in late July to mark the 70th anniversary of the Korean War’s armistice.

Earlier this month, U.S. National Security Council spokesman John Kirby said that Shoigu's visit had been intended to "try to convince Pyongyang to sell artillery ammunition" to Moscow. The U.S. said high-level talks on military cooperation between the two countries have continued following Shoigu’s trip — the first by a Russian defense minister since the Soviet Union collapsed.

The anticipated meeting comes almost a year since North Korea denied that it was considering providing weapons to Russia after U.S. officials warned that Moscow was looking to buy "millions" of rockets and artillery shells from Pyongyang.

North Korea has long held massive stockpiles of munitions to both deter and prepare for a war with South Korea, experts say. Although estimates vary, Pyongyang's stockpile of artillery shells is thought to be in the millions — though a large portion of these shells are aging and of questionable accuracy and condition.