The United States has accused North Korea of supplying battlefield missiles and rockets to the Russian mercenary group Wagner for use in Ukraine.
The White House said the shipment violated UN Security Council resolutions and that it would announce further sanctions on Wagner.
However, Both North Korea and Wagner have denied the reports.
Fighters from the mercenary group have ballooned from 1,000 to nearly 20,000 in Ukraine.
The group has also been active recently in Syria and African countries, and has repeatedly been accused of war crimes and human rights abuses.