Vladimir Putin and Kim Jong Un are getting closer — and China has reason to be worried

• Russia entered into a new security pact with the rogue state North Korea. 
• It's an alliance probably being viewed with caution in Beijing, analysts say.
• China is eager to avoid a flare-up on the Korean peninsula, they say. 

Russian President Vladimir Putin and North Korea's leader, Kim Jong Un, recently signed a defense pact to protect against what they characterized as the malign forces of US imperialism.

But it's not just the US's allies in East Asia that appear alarmed by the new alliance between the authoritarian leaders.