[Have you ever heard of NATO?]
NATO came out after Russia had nukes.  China is nowhere near any NATO member states when they got the nuke.  IIRC, none of the member states today are neighbors to China, India or Pakistan nor "threats."
[SEATO]
Defunct and was a political "defensive" treaty to combat communism.  Again no "threat."
[Japan-U.S. Security Treaty]
Japan was the aggressor in the Sino-Japanese war so no threat.  I would also argue that they are not neighbors in the same sense that NK and SK are.