SEOUL, South Korea (AP) — North Korea has denied American claims that it’s shipping artillery shells and ammunition to Russia for use in its war against Ukraine, and on Tuesday accused the United States of lying.

The denial follows dozens of weapons tests by North Korea, including short-range missiles that are likely nuclear-capable and an intercontinental ballistic missile that could target the US mainland. Pyongyang said it was testing the missiles and artillery so it could “mercilessly” strike key South Korean and US targets if it chose to.

North Korea has been cozying up to traditional ally Russia in recent years and even hinted at sending workers to help rebuild Russian-occupied territories in Ukraine. The United States has accused North Korea, one of the most weaponised countries in the world, of supplying Soviet-era ammunition such as artillery shells, to replenish Russian stockpiles that have been depleted in the Ukraine.

Last week, Russia sent North Korean leader Kim Jong Un a trainload of 30 thoroughbred horses, opening the border with its neighbor for the first time in 2 1/2 years. Kim is an avid horseman and state media have often pictured him galloping on snowy mountain trails astride a white charger. The horses, Orlov trotters, are prized in Russia.

Spokespeople of Russia’s Far Eastern Railway told the state-run news agency November 2 that the first train headed to North Korea with the 30 horses and said the next train was to carry medicine.

Experts say North Korea may be seeking Russian fuel and also technology transfers and supplies needed to advance its military capabilities as it pursues more sophisticated weapons systems.

In September, North Korea restarted its freight train service with China, its biggest trading partner, ending a five-month hiatus.

Last week, US National Security Council spokesperson John Kirby accused North Korea of covertly supplying a “significant number” of ammunition shipments to Russia. He said the United States believes North Korea was trying to obscure the transfer route by making it appear the weapons were being sent to countries in the Middle East or North Africa.

“We regard such moves of the US as part of its hostile attempt to tarnish the image of (North Korea) in the international arena,” an unidentified vice director at the North Korean ministry’s military foreign affairs office said in a statement carried by state media.

“We once again make clear that we have never had ‘arms dealings’ with Russia and that we have no plan to do so in the future,” the vice director said.

In September, US officials confirmed a newly declassified US intelligence finding that Russia was in the process of purchasing millions of rockets and artillery shells from North Korea. North Korea later dismissed that report, calling on Washington to stop making “reckless remarks” and to “keep its mouth shut.”

On November 2, Kirby said the US has “an idea” of which country or countries the North may funnel the weapons through but wouldn’t specify. He said the North Korean shipments are “not going to change the course of the war,” citing Western efforts to resupply the Ukrainian military.