For months, the U.S. has warned Iran not to send ballistic missiles to Russia and told China not to provide military components for Moscow’s war in Ukraine.

But Iran is now doing just what Washington said not to and China is pushing the line. Indeed, the U.S. and its allies are increasingly worried by the speed and intensity with which the three, along with North Korea, are deepening ties to challenge American dominance despite facing some of the most sweeping sanctions the West has ever imposed, according to officials who asked not to be identified discussing matters that are not public.

The defiance fits a pattern of what outside experts — and increasingly, U.S. and allied officials — see as the growing struggle Washington faces as its seeks to get what it wants around the world.