The outspoken sister of North Korea’s leader blasted accusations her nation is exporting weapons to Russia as a “fiction,” shortly after the U.S. imposed new sanctions on the arms trade that Washington says is powering the Kremlin’s assault on Ukraine.

“The hostile forces are misleading the public opinion with a false rumor that the weapon systems produced by the DPRK are ‘for export to Russia’,” state media on Friday cited Kim Yo Jong as saying. “We have no intention to export our military technical capabilities to any country or open them to the public.”

Despite international sanctions that bar Pyongyang from exporting its weapons, a multitude of satellite photos released by research groups and the U.S. government have shown a flow of arms from North Korea to Russia and then to munitions dumps near the border with Ukraine.

Shortly before the statement from Kim Yo Jong, the U.S. Treasury said it had imposed sanctions on five Russia-based individuals and entities that are “connected to the transfer of military equipment and components” between North Korea and Russia.

The Treasury statement said Russia has used upwards of 40 ballistic missiles from North Korea in its attacks on Ukraine as well as munitions from the country in contravention of United Nations Security Council resolutions.

The U.S., South Korea and others have accused North Korea of sending its newest nuclear-capable ballistic missiles to Russia. These have a reputation of being easy to hide, quick to deploy and hard to shoot down. Images from missile debris in Ukraine indicate they are Hwasong-11s, a wide class of short-range ballistic missile that can reliably hit targets, weapons experts say.

In addition to the missiles, the U.S. and its partners have accused North Korea of sending millions of rounds artillery to Russia, which have proved crucial to Russian President Vladimir Putin’s forces in a conflict where massive amounts are expended daily. Ukraine’s ammunition stocks have dwindled as delays in the U.S. Congress hold up shipments, forcing Kyiv to ration their use.

Leader Kim Jong Un in recent weeks has overseen weapons tests and visited plants in the munitions trade, showing off North Korea’s systems.

South Korean Defense Minister Shin Wonsik has said the images may be also intended to promote weapons sales to Moscow, which have stepped up since Kim visited Russia last year for a summit with Putin.

Russia in return is providing North Korea with food, raw materials and parts used in weapons manufacturing, South Korea’s Shin said, adding the food aid has helped Kim stabilize prices for necessities. If the arms transfers grow, Russia will likely send more military technology to Kim, increasing Pyongyang’s threat to the region, he said.

The artillery alone is likely worth several billion dollars and the aid from Russia could represent the biggest boost to North Korea’s economy since Kim took power about a dozen years ago.

Worries about the arms trade have increased as the normally reclusive North Korea has been sending high-profile delegations to Russia as well as Iran, which has a history of arms transfers with Pyongyang dating back several decades. North Korea this week sent a science delegation to Russia for a trip that stoked concerns of cooperation on weapons and technology.

During their summit in September, Putin pledged to help Kim with his plans to put an array of spy satellites into orbit to monitor U.S. forces in the region. The Russian leader also pledged to visit Pyongyang, though no date was set for the trip which would be Putin’s first to the North Korean capital in more than two decades.