The United States and nearly 50 countries on Tuesday condemned North Korea's alleged transfer of missiles to Russia.
They also demanded an immediate end to the cooperation.
The U.S. last week said that Russia, short of weapons nearly two years into its invasion, attacked Ukraine with missiles from North Korea, which is under a slew of international sanctions for its missile and nuclear work.
In a joint statement, Secretary of State Antony Blinken was joined by EU foreign policy chief Josep Borrell and 47 foreign ministers in condemning the alleged transfer in "the strongest possible terms."
"The transfer of these weapons increases the suffering of the Ukrainian people, supports Russia's war of aggression, and undermines the global non-proliferation regime," said the statement released by the U.S. State Department.
They said the alleged missile shipment "flagrantly" violated sanctions on North Korea by the United Nations Security Council, of which Russia is a permanent member.
"We are closely monitoring what Russia provides to the DPRK in return for these weapons exports," said the statement, referring to the North by its official name, the Democratic People's Republic of Korea.
They called on the two countries to abide by Security Council resolutions and "immediately cease all activities that violate them."
The 47 countries that signed overwhelmingly came from Europe and also included South Korea and Japan, treaty-bound allies of the United States.
Other signatories include Israel, which has been cautious in its statements on Russia – heavily involved in neighboring Syria – but also has counted on U.S. support in its three-month brutal military campaign in Gaza.