A meeting of the U.N. Security Council on June 28 will see the U.S. confront Russia over violating a North Korea arms embargo, Deputy U.S. Ambassador to UN Robert Wood told Reuters.
Pyongyang has since 2006 been under a U.N. ban from importing and exporting weapons.
For nearly two decades, Russia, as part of the U.N. Security Council, supported the sanctions, aimed at restraining its nuclear ambitions.
But facing reduced military stocks and production capacity simultaneously hampered by its own Western sanctions since the launch of its full-scale invasion of Ukraine, Russia has increasingly turned to North Korea.
New internal Russian trade data obtained by the Washington Post showed Russia may have received 1.6 million artillery shells from North Korea over the course of six months, and the U.S. has previously accused Moscow of firing North Korean ballistic missiles at Ukraine.
The relationship between Moscow and Pyongyang was cemented last week when Russian President Vladimir Putin met with North Korean dictator Kim Jong-Un to sign a mutual defense agreement between the two countries.
Speaking to Reuters, Wood said Washington will confront Russia over the issue at the U.N. Security Council meeting on June 28.
"This should be of great concern to the entire global community," Wood said, accusing Russia of "in essence siding with a rogue state to violate countless U.N. Security Council resolutions."
"This is unprecedented, and we need to call it out for what it is," he said.
Wood said the issue would also be raised with China to see what Beijing "has to say about this growing military cooperation between DPRK and Russia."
"They cannot view this as a positive development," he added.
On June 19, the two signed a mutual defense agreement during the first in decades visit of Putin to North Korea.
The pact declared in part: "In case any one of the two sides is put in a state of war by an armed invasion from an individual state or several states, the other side shall provide military and other assistance with all means in its possession without delay."
The agreement also covers trade, investment, political and security cooperation.
In response to the announcement, South Korea said it would reconsider supplying weapons to Ukraine.
Chris York
(Updated: )
