Heyhey, Ask me this questions man! I am Malaysian!
Ok, my story starts from THE COLD WAR. During that time Malaysia was not on any side of the 2 great powers. Malaysia united all the ASEA regions and built a ZOPFAN (In Malay words it's "Zon Aman,Bebas, dan Berkecuali". Which means "Peace,Free,and Neutral Zone") body. So the whole ASEA did not depended on anyone or on anyside either under this body objective. Until today this ZOPFAN still remain there.
ZOPFAN contains something like "not allowing USA to send nuclear weapon" through the ASEA sea (Melacca strait more specifically). Freely to have diplomatic relations wif either communist or decromatic countries (Malaysia were the first country to have diplomatic relationship with China if I am not mistaken,and before this we already had diplomatic relationship with USA, Britain, etc)
So when there's a future war between this 2 great Nations, whole ASEAN region will just remain neutral. ZOPFAN will still take place.