Carnegie assesses cooperation among China, Russia, Iran, and North Korea as a strategic risk for the United States, while warning that the four states are not yet a coherent bloc. The North Korea-relevant section says Iran and North Korea have shared defense technology, especially ballistic missile expertise, with reported similarities between Iranian and North Korean missile systems and some joint manufacturer projects. The paper also cites North Korean weapons reaching Iran-backed groups, including grenade launchers used by Hamas and attempted Scud C and Burkan-1 missile transfers to the Houthis. Its main judgment is cautious: deeper cooperation is possible, especially around Russia's war effort and military technology, but current cooperation remains mostly bilateral and limited.