As thousands of North Korean troops deploy to Russia for use in its war with Ukraine, China is left particularly uncomfortable by the swift militarization of ties between Pyongyang and Moscow.

The United States on Monday called out Russia and China at the United Nations Security Council for "shamelessly protecting" and emboldening North Korea to further violate U.N. sanctions as Pyongyang pledged to accelerate building up its "nuclear force.

American agencies have assessed that China dislikes the growing partnership between Russia and North Korea. The State Department has raised the troop issue with Chinese diplomats.