Jake Sullivan U.S. National Security Advisor leaves after meeting Ukrainian President Volodymyr Zelenskyy at the Annual Meeting of World Economic Forum in Davos, Switzerland, Jan. 16. The annual meeting of the World Economic Forum is taking place in Davos from Jan. 15 until Jan. 19. AP-Yonhap

U.S. National Security Advisor Jake Sullivan and the secretary general of the North Atlantic Treaty Organization (NATO) expressed concerns over North Korea's export of military equipment to Russia for use in Ukraine during their talks in Washington on Monday, the White House said.

NATO Secretary General Jens Stoltenberg was in Washington to discuss maintaining support for Ukraine and preparations for the NATO summit slated to take place in the U.S. capital in July, among other issues.

"They exchanged views on allied progress in ramping up defense production and expressed concern over the DPRK's export and Russia's procurement of DPRK military equipment, as well as Russia's use of this equipment against Ukraine," the White House said in a readout.

DPRK stands for the North's official name, the Democratic People's Republic of Korea.

The White House has said that Pyongyang provided Moscow with several dozen ballistic missiles for use in Ukraine in addition to its earlier supplies of military equipment and munitions.

Seoul, Washington and other governments have criticized arms transactions between the two countries as a violation of multiple U.N. Security Council resolutions banning arms trade with Pyongyang.

During Monday's talks, the two sides also welcomed Turkey's recent approval of Sweden's NATO membership and expressed a shared desire to see Sweden join the transatlantic alliance as soon as possible, according to the readout.

"Secretary General Stoltenberg noted NATO's Allies' unflinching support for Ukraine as it continues to defend itself against Russian aggression," it said. (Yonhap)