Analysis by Simone McCarthy, CNN

The thousands of North Korean troops US intelligence says arrived in Russia for training this month have sparked concern they will be deployed to bolster Moscow’s battlefront in Ukraine.

They’ve also turned up alarm from the United States and its allies that growing coordination between anti-West countries is creating a much broader, urgent security threat – one where partnerships of convenience are evolving into more outright military ties.

Hundreds of Iranian drones have also been part of Moscow’s onslaught on Ukraine, and last month the US said Tehran had sent the warring country short-range ballistic missiles as well.

China, meanwhile, has been accused of powering Russia’s war machine with substantial amounts of “dual use” goods like microelectronics and machine tools, which can be used to make weapons. Last week, the US for the first time penalized two Chinese firms for supplying complete weapons systems. All three countries have denied they are providing such support.

Taking stock of the emerging cooperation, a Congress-backed group that evaluates US defense strategy dubbed Russia, China, Iran and North Korea this summer an “axis of growing malign partnerships.”