Because they’re not idiots. They have no interest in emboldening the US empire and weakening their Russian ally. In a hypothetical scenario where the US win in Ukraines, it is likely that a comprador regime reminiscent of the Yeltzin dictatorship would be installed in Russia which would be a national security disaster for China.
Also, since China is not ruled by idiots, they realise that the Kiev government has no viable way to victory and that prolonging the war doesn’t support Ukraine but only leads to more death and destruction.
Because they’re not idiots. They have no interest in emboldening the US empire and weakening their Russian ally. In a hypothetical scenario where the US win in Ukraines, it is likely that a comprador regime reminiscent of the Yeltzin dictatorship would be installed in Russia which would be a national security disaster for China.
Also, since China is not ruled by idiots, they realise that the Kiev government has no viable way to victory and that prolonging the war doesn’t support Ukraine but only leads to more death and destruction.